I hate myself with every fibre of my being and I don't think it will ever get better
Why would you think like that? You can get better.
I met a disabled person that has the same hopes and dreams as I do, she taught me that no matter who you are everybody can achieve something
The person you met is correct. There is no need to hate yourself, and things will get better if you keep trying.
I've done that already but nothing has changed
Then you have not been doing the right things. You should not give up on yourself, you have the ability to change.