While in therapy the other day I was being asked about details about how I felt after I got home last week after fighting with my boyfriend and then having a really emotional therapy session. She kept wanting details and I could not give them to her. I really can’t remember what happened or how I felt beyond the vague basics. 
She says I dissociate when I’m upset, which is why it feels like I’m almost a different person when I’m down than when I’m happy. She is probably right, but I’m not entirely convinced. When I’m upset I don’t feel like I “go away” and that I need to stay grounded. I do the opposite; I get so locked into my own head/thoughts that I can’t talk about anything or really do anything. 
Is it the same thing? How can I tell when I first start dissociating so I can try and stop it?