Here are the thoughts of a mom with a very nearly 15yo daughter.
I believe that in today's world, it's imperative that we teach our children how to responsibly use credit cards -- BEFORE they go off to college and get one for "emergency" purposes only. Yeah, right.
There are MANY times that teens need something other than cash, which can be cumbersome to carry. Another practical use...your child goes to the mall with friends. Stick some money in their account and tell them to get that pair of shoes they need while they're there. It's sometimes hard to figure out enough to give them, and most of us adults don't carry enough cash to give to our kids anyhow.
I really don't see this as being the "cool" thing to do. It really is necessary these days.
I really think you ought to get a card through your bank. Forget the other cards. You mentioned your mom upgrading your account. That's what I would do. Either that or open another account just for this purpose and opt for a debit card to be issued. If your parents have an account at the bank, they should be able to transfer your allowance from their account into your's (even online, if you have online banking). Talk to the bank about what your overdraft options are. They deal with this stuff every day. If you don't like the options your bank has, visit other banks.
Storytime: DD went w/soccer team to out-of-town game. Team stopped for lunch at Cracker Barrel instead of McD's. She only had enough money for fast food (bad parents...ran out of cash and couldn't get to the bank before she left that morning). What to do?? I had to call the manager and explain the situation and ask if they could punch in my credit card # at the register so she could pay (I asked before she ordered so she wouldn't be embarrased if they said no). If she had her own card, this could have been prevented.