Using the DCA method in investment will indeed be very profitable and we can invest according to the income we have after meeting the needs we need and it is also very profitable if we can do it consistently to be able to enjoy profits if we feel sufficient for the investment we have made we do.
I am very interested in trying to invest like you have done, but at the moment I do not have the income to be able to invest because the income I have is only enough to be able to meet the needs I need and I will continue to work to be able to do what I have done, you do that.
First of all you don't need any money to plan investment you think you don't have money now but you will definitely have money in future and then you can invest in Bitcoin for long term. Even if you don't have money now, you can try to get an idea about investing now. You try to get an idea in advance about how strong you need to be mentally or how much financial risk you have to take when investing in long-term plans.
Investing will be much easier for you when you know about such things in advance when it comes to keeping your investment for a long time.
As you said that you don't have enough money to invest and the amount of money you have is for running your family but I will tell you that you need to accumulate a lot of money to invest but not talking. You can start investing in your long-term plans with the money left over from household expenses. You may think that investing a small amount of money can be profitable, but when you invest this small amount for a long time, your idea will change.
From the way you describe your finances, I assume you have at least $10 left over at the end of the month after family expenses, which is enough to invest. If minimum 10 dollars can be invested regularly then after five to seven years your total investment amount will be much higher and I believe when you start investing you will not invest 10 dollars every month but you can invest more amount then.
People's financial condition is not always the same, maybe your financial condition may be bad now but your financial condition will be better in future so start investing from now and keep doing consistently when you have more money you can increase your investment amount.