I'd suggest waiting until you don't have any inqs or new accounts in the last 6 months. If your mom can add you back to the amex and other of her oldest accounts, it will help lots.

After the 6 month cleanup, I would go for boa and wells Fargo Students and Walmart card.
I didn't get how much you make a year, so I can't suggest amex.
I don't recommend discover students as the low limit they give students will haunt you forever.