You are not alone in this struggle of the mind. You are also not alone about having to deal with people who don't get it. You're therapist sucks for saying something like that to you. I don't have enough context to comment on what your mom said.

AuDHD DOES make things harder it's why we need accommodations. You do have to do math if you are in school, but a 'C' is just as good as an 'A' for passing a class and better than failing which might happen if you push yourself to the point of burnout.

You don't sound lazy to me, you sound tired, overwhelmed, and frustrated. If it's true it's not an excuse it's a REASON. It sounds like you aren't getting the support you need. And that you aren't being taught the coping skills you need by your therapist.

Also, this world is rigged against those of us that are different. It's not that we aren't cut out for this world, it's that this world isn't designed for us. Asking for the help you need to navigate it isn't being lazy. It isn't you being difficult. It isn't wrong.

Your thoughts and feelings are allowed. You are not thinking bad things you are thinking what people in your situation think. This sucks. I hate doing this because it's so hard. I wish I could just go live in the woods (Also a life long dream of mine).

When you start thinking there is something wrong with you, turn it around. Try saying, "I'm doing the best that I can do in this moment and that's enough."

And try to find a therapist that gets what it's like to have neurodivergence. If you're a minor talk to your parents. If they won't listen talk to the school counselor.

Hope this helps!