Because you have her address, do a search and find the home phone number listed with that address. Give her parents a call and explain the situation to them. You will probably receive either the stickers or your money back very quickly. If you can't figure out how to find the phone number, PM me and I will help.
If for some reason we cannot find the phone number, send a letter addressed To the Parents of _____ _____. It might seem low getting her parents involved, but what she is doing is lower. Also, please post her home town. For example, just let us know not to buy any die-cuts from Topeka, Kansas. This protects her identity, but still prohibits her from just making another account to sell stickers/scam. The e-mail address you sent payment to via PayPal might be nice as well. Hell, she scammed you, just post her name if she doesn't come through in the next 7 days. No mercy for the guilty.