I hate how my dad "encourages" me to learn

[Aoi Magi]

DA, from what you said I feel there is a bit of a communication gap between you and your parents, you seem to keep wondering why your parents don't seem to understand that you are trying your best, well from what you said, it is because you are not telling them that. Parents are not psychics and won't know your thoughts or problems if you keep hiding them! Yes they might, or rather let's say they will overreact, and you might get a few more very long speeches, but it's better to hear those from your own parents, rather than outsiders! Moreover, once you do let your parents know, they will do their best to get you the help you need, and the earlier you get help the better off you'll be in your life. So you must gather the courage to let your parents know and if you are really afraid to do so alone, get help from a sibling/cousin/friend, or even a letter might work, but you've got to let your parents know!

I told him numerous times that I try my best, this doesn't calm him down at all

No, not just that, you've got to tell him about your mental health as well as how his speeches are affecting you. If it doesn't work, tell it to your therapist and enlist their help in mediating between you and your parents.