Someone unpack my trauma

(21F) To keep it short and sweet i have some sexual trauma from past relationships w SA from when i was 15 and blah blah but ive tried talking about it in therapy and it hasn’t done me all that well and ive tried to enjoy sex and sometimes it can be good and fun and sweet but the thing that has been bothering me so much is that i think sex is so much better when I’m not in a relationship with someone. Like before we date it’s great and then whenever there’s a label it’s like i get so anxious about it and it doesn’t have the same appeal and i overthink and maybe it’s because i feel like my partner expects it? The one relationship i had where i truly loved that person we didn’t have sex and we dated for a long time (i couldn’t get myself to i would freak out) and he was fine with it and never pressured me or held it against me ever. Anyways. Someone tell me why im like this i feel like i cant even talk about this with my therapist