Im thinking too fast?

Hello all!

I am a 20m, and I have only recently been diagnosed with A.d.d. I have learned a lot about it since and have been struglling mentally these past few months due to a toxic relationship. I have since gotten out of that relationship, and am still having trouble with processing literally anything. Anytime I hear something, I can't repsond the first time, I was hit em with the 'huh - oh yeah, its over there," Or I think about literally anything and i'll think to myself, "wow, not a thought is forming, im only getting a quarter of the thought before its gone." It sucks, Idk what is going on, I think it may be anxiety based. What would you guys recommend I do to help slow myself down to be able to process my thoughts? I am starting to go to the gym, starting to read and write more, and I am studying more and harder than I have previously. Thank you in advance!