I'm 21 lol but I can't afford to move out because I'm a student. I hope your parents have an interest in reptiles because your red tailed boas can get pretty big even if their size doesn't seem like a lot. I wanted a boa for so long but my parents would never let me get one. Eventually I held a full grown female at All reptiles when I was about 16 and I decided they would be too much for me until I was older. I could probably handle them now but I won't get any until I move out both because of my parents and the space they need.
I think if your parents are on board you should be allowed to keep reptiles regardless of your age and regardless of the species (excluding venomous). If they aren't then you should probably avoid anything that gets too big or is too aggressive for you to handle on your own.
It's hard to know what you'll want to do when you're say 21 if you're 11, I've seen a lot of people get into and out of the hobby quickly regardless of their age but I also remember how much I loved reptiles when I was your age and although I fell out of this hobby for awhile I'm back into it as strong as ever now.
Anyway I guess the tldr version of my statement is age is just a number, it's more about your personality and attitude, however it's incredibly irresponsible of you to own anything you can't take care of on your own if you know you won't have anyone to support you. Just my 2 cents.