Since you are interested in Bitcoin investment, your current Bitcoin amount may be small, but it will eventually grow if you continue to accumulate Bitcoins as much as you can.
OP only bought around 15$ worth of bitcoin the first time. The coin's value will have to go up to $44.000 for him to double his money. Even if/when it does, he will only profit around $15 on that trade. I don't know where OP lives, but in most parts of the world, you can't get much done with $15 in your pockets. It's good to start somewhere, but one soon realizes that small investments like that aren't worth it.
Indeed, even if he comes from the poorest country in the world, $15 or $30 won't do him much good. I'm not saying his investment is useless, but he needs to replenish his investment every time he has money and requires more than this if he wants to get substantial rewards back. Bitcoin is a potential investment that can give us significant returns but not an investment that will make us rich with a small amount of capital.
Bitcoin used to deliver thousands or hundreds of thousands of percent returns in the past, but that is no longer the case. So if someone is looking for an investment that can yield such huge returns, bitcoin is not an option.