It’s funny reading this because I was just like this well into my twenties and didn’t have a dx at the time. I’d rely on my mum to ask me helpful questions to find my way into an essay subject and keep me focused and listen to my anxieties. But then if she didn’t seem to instantly get what I was talking about or what kind of work was expected of me (bearing in mind she doesn’t know the subject beyond what I tell her) get irritable and lash out and start freaking out generally. She was very patient because I think she understood that something was making it hard for me, but it can’t have been fun.
Maybe you and your family can work on ways of recognising when you’re getting frustrated and short-circuiting the feeling. Either by doing something soothing like going outside or stroking the cat, or if necessary talking through your feelings. Try and talk dispassionately without boiling up – it gets easier with practice – as this will help you think through your situation without catastrophising. Then you’ll have an easier time putting your worries to one side and focussing your attention where it’s needed.
However, my problem was more with executive function than understanding concepts – so as a poster above said, professional help may be more appropriate.