How it's even make sense to invest more when you're not even confident with the current money you've invested?

Only invest what you can afford to lose, if you feel an emotion, it's better to reduce the amount you invested. If you still worried, it's better if you learn about Bitcoin and find a good reason to trust it.

What if you've reduce the invested amount, learn about Bitcoin and still not convinced in Bitcoin? that means you shouldn't invest in Bitcoin.

first thing to keep in mind. if you have no intention to sell every month. there is no need to be watching the price daily
so stop watching the prices daily

you have already admitted to wanting to invest monthly so just concentrate on when to buy, dont watch the price for when to sell

as for how much to invest
dont invest more than you need to live on

set a budget
open a spreadsheet and input how much income you get.
write out all your essential bills. and then write out all your other expenses.
calculate how much you can live on if you deduct out some wasteful spending to then have some spare income
this spare income which would have just been wasted is what you would invest

as for idea's like DCA.
people investing in fiat plans like pensions do DCA because they deposit into a fund manager and that fund manager does the hard part of looking at a group of investments for the one that has the lowest market price for the year, and invest most in the low's and less in the highs
(the practice of buy low sell high)
so look at a bunch of investments that have proven longevity and utility. and then look at which ones you should invest most in and which ones to invest least in

many PoS coins are speculated way too high in premium price above their means. they cost only a few dollars to mint new coins but speculate too high on the markets (ethereum costs only $50 to mine new ether at hardware+electric cost but speculates above $2000)

bitcoin however has more market potential to grow. in some island area's of the pacific (japan/hawaii) bitcoin mining cost is above $140k per btc so the market has alot of potential growth of people willing to buy over say $120k as its still cheaper than mining. bitcoins efficient mining cost is $25k
so the window of
bitcoin
   $25k                    $140k
||||||||||||||||||||||||||||
         ^
ethereum
$50                        $4.6k
|||||||||||||||||||||||||||
              ^

so figure out the mining/minting costs of cryptos (their most efficient($0.04/kwh) and least efficient($0.50/kwh)* mining/minting equipment cost)
then look at where the current market price is within those windows of speculation, and invest more in the ones with alot more market potential for growth using sound logic of mining/minting costs

First, decide if you're in it for the long term or short term. Based on what you've mentioned, it seems like you're keeping an eye on the market, which aligns more with a short-term approach. If you're aiming for the long term, there's no need to constantly monitor the market to avoid fear of uncertainty (FUD), which I think you are already experiencing.
Long-term investors focus on accumulating Bitcoin over time and worry less about market fluctuations. Personally, I haven't checked the Bitcoin market for days, and I just woke up to find it crossed the $45,000 mark. This illustrates that as a long term holder, occasional price checks are sufficient, reducing the need for constant monitoring.

 If you're considering investing, only invest what you can afford to lose, given the market's volatility.just watch the market less often and you will see the sweet spot about investing in Bitcoin

It is Very much interesting that you know the potentials of the Bitcoin markets volatilities.
There wouldn't be an affirmed fix amount anyone would ask you to Invest on from your incomes. You know better how much your income is but here what is paramount and best advisable is that you should start your investment with a minimum amount of fund you can afford to tolerate with the fluctuations nature just as you are being aware.
Hence I would say you are not going to loose your funds as long you are well responsible and careful to keep your private key phrases safe rather you only need the ability to tolerate at when then market price goes contrarily against your will and you can only achieve a bat by investing with a tolerable amount of capital.
So, it is best known to you to figure what your income is and how much you can afford as a gambling of gambling.

^sounds like dave ramsey plan

I can not possibly tell you how much should you invest from your monthly income i mean i do not know your monthly expenses do you have a family that you are providing for? Any kids or no kids? Are you paying off any loan? It is a complicated question

If you are unsure of the amount you should put in into investment then just do not put that amount if you put too much of an amount you might scare yourself and be easily swayed once FOMO hits it’s either you get over the uneasy feeling of investing your money in order for you to invest with how much you want it to be or you settle for the amount of money you are only comfortable with putting out i do not think there is anything wrong with either one but of course the first situation guarantees more profit however the second situation also helps you to not recklessly put out money

Before investing in Bitcoin, you must calculate your income and expenses. You will know how much money you still have left from the results you get. From the remaining money, you can decide how much money you can use to invest in Bitcoin.

When you have a certain amount of money you can invest in Bitcoin, you don't think about the ups and downs of the ever-changing market. You can use the DCA method to invest in Bitcoin to be calmer against ever-changing market conditions. You won't panic if the price of Bitcoin decreases because you already have a schedule for investing in Bitcoin, and it does not depend on what the price of Bitcoin is in the market.

If you can only invest in Bitcoin using $20 every week or $50-$100 every month, you can use DCA to invest in Bitcoin regularly. That already prevents you from thinking about Bitcoin price changes. You can also focus on your life because your investment in Bitcoin is still going according to plan.

Emotion must not taKe place when you invest in bitcoin because this market is only for
tough and capable of risking and not the drama way of life because you will only lose here and will
never gain if that is your behavior .
or maybe he needs to close her eyes for a while to not see how much the market changes
because that is the reason why he will change his emotions like rollercoaster ,

Right. It's true that having a stable source of income can provide a sense of security in crypto investing. While Bitcoin is often considered a safer option, emotional decisions can still arise when risking more than one can afford to lose. we should still approach any investment with careful consideration and a balanced mindset.