I'm not sure if your therapist can help you with this, but I find it helpful to have a few alternate words on standby just in case I block on a word I'm trying to say. For attendance I've used my first name only, last name only, or even just "Here." Because those three are different enough pronunciations, I can usually work through a block. If that doesn't work, just raise a hand. It'll be alright. Find something that works for you! Edit- /u/Odd_Ladder7024's advice is sound. Talking to your professors about your situation is a very powerful tool. 9.9/10 times they'll be on your side and will want to find a way to make sure you can feel welcome and succeed in their class.