I don’t know what kind of stores you have in CA but in New york you can find those kind at a Sporting goods store. In New York we have two Modell’s and Sports Authority if you have those or similar store you might be able to find them. Some time you might get one at JC Penny’s or go to LL Bean’s web site or Lands End any of those places have them and They may seem like a lot of money at first but my daughter still has her LL Bean from fourth grade she’s just out grown it. So now she uses it for storage,

There was a study that came out last year about the degrading health of the backs of young people. The study through research proved that students should not carry more than 25lbs on their backs for any length of time. With your scoliosis, that number would most definitely be less. What happens when you add the weight of a backpack is it puts immense pressure on your spine and throws your back out of alignment. While you may not feel any repercussions immediately, the effect over time can be very health threatening. Compromise with your parents. Ask if you can buy a set of books to keep at school in your locker and keep one set at home. That way, you can carry the lighter sling type backpack (proven to be a better weight distributor) with just your spiral and notebook. Considering your scoliosis, the school may be willing to issue you the double set for free – contact the school nurse for support. Good luck