reptiles is not for the young and unemployed unless your parents are willing to fund your interest (which is sounds like they do not). #1 the vet bills are expensive #2 the labor and lifespan needs a lot of dedication (20+ years)
I have spent over $900 in the past year and a half on reptiles alone so let your brother know that the initial start up cost will cost him a few hundred dollars if he is lucky.
a mammal would be a better pet in your situation since they only need food, water, and have a short lifespan. maybe a cat or guinea pig?
We do not mean to "yell" at you but when someone says "I dont have the money or room for the pet I just brought home" then we see that as a death wish for the animal. no turtle can live comfortably in a 20 gallon tank with no lighting. It may live 6 months at the most in that condition.
p.s. it seems like you already have a frog (from your avatar picture). I would stick to the frog for now until you get a part time job. I started working when I was 14. I have tourettes so it is hard to function in a social environment, but I pulled through it. you will too.