With a full obstruction, you wouldn't be able to pass any gas or stools at all, and it would be DANGEROUS to ingest anything at all. By this time, hopefully the prednisone is helping you somewhat, but if you start vomiting again, get terrible cramping, or stop passing gas/stool totally then you should go to the ER. A full bowel obstruction is a medical emergency.
Either way, your symptoms sound very serious. When is your next appointment with a doctor?
If you do have to get surgery, it doesn't necessarily mean that you need a stoma or a bag. I had surgery less than 1 month ago and they just cut out the stricture and then sewed the intestine back together, and I'm feeling really good.
Generally speaking, with surgery, you'd have to take off at least 3 weeks from school, and most schools have certain policies for medical stuff, so check in with your teachers about it if you need to. Maybe they can give you assignments to do while in the hospital so you can stay caught up?