I cannot really judge you (or your performance) from here, but surely I can say a thing or two about your supervisor's behavior:
Given that they are supposed to be managing and guiding you (you're being a new recruit in an entry level position), and them saying things like He doesn't know if I can fix what's wrong even if I tried and qualifications weren't good enough for this job when they were part of the interview process and asking to sort out problems about your (already known) disabilities - they clearly lack leadership and management skills.
Also, as mentioned by your co-worker, if they are being particular about you in finding faults and suggesting directly that you should look for opportunities elsewhere - I believe they are not being / willing to be welcoming, at all.
It's very very difficult to improve upon, if you don't know the shortcomings. If the person who is in charge of guiding you and helping you grow is not interested in doing their job, then they are at fault for sure - but you also need to asses how that is going to affect you and your career.
Usually I'd have suggested to have a formal discussion with your superior and ask for pointers to improve upon - but that's already happened and nothing positive came out of that.
If I were you, I'd be inclined to excuse myself from this environment and look for opportunities elsewhere, where a better work environment and supportive superiors are expected to be there.
Also, as a learning, I'd suggest to make a self-note about setting the priorities and responsibilities right at the very beginning. Whatever be the scenario is, having a clear goal set always helps you to asses or answer about the performance delivered by you - even if others (your supervisor, leader or reporting manager) are not interested, you should insist on getting it done and make sure both the parties agree upon the goal. That really helps you out at later stages.