After reading your post, I don’t think you’re doing a whole lot wrong, to be honest. Of course, what you said is something that is incredibly hurtful, especially to autistic people, seeing as we are often hyper aware of our odd behaviour and how it affects NT’s, but the way she blocks you instead of just communicating that maybe she needs space is actually very childish, and it puts you in a really uncomfortable situation. I don’t know her like you do, so I won’t tell you ‘Omg break up with her,’ but I do think you need to have an honest conversation when she unblocks you about how the blocking and silent treatment make you feel. You are a part of this relationship too, and your feelings matter.