I'm really sorry to hear that.
I have never had such experiences, since I am either liked or just unnoticed by teachers (I am the average quiet student), however I do understand what you mean and I get where you are coming from. I would probably be making the same assumptions in your situation, since I tend to over analyze and worry a lot.

I mean, teachers should not have favourites and least-favourites (Or at least not show it) and you are right, as a student you have every right to put your hand up and ask for help. It shows you care enough about what you're learning. Not only that, but it is their job to help you, as a teacher.

I could tell you to tell the teachers directly how you feel, but on the other hand I know it's not easy- certainly easier to say than to do. And it is quite upsetting how even your peers end up ignoring you; you can't even discuss it with them. I'm not really sure what advice I could give, except a bit of a confrontation. Maybe instead of face-to-face, write then a polite but to-the-point email. If you don't want to address them directly, them maybe contact a different teacher you would be okay with?

Don't have any other advice for now. Hope it helped at least a little bit though.