Overthinking it or can I let this go ?

So me and my cousin whom is male and I'm female are the same age , he is a extremely open honest person I'm more reserved we talked about our sex lives and our experiences what we like don't like with our partners ,because I'm so reserve he said its healthy to talk about sex and to have a healthy mindset about it and friends can talk about that sort of stuff so we where just asking each other questions what age we lost our virginity what we like that sorta stuff , then he asked my bra size I Said I don't wanna anwser that because that's my body and I don't think it's right to anwser that he said that's fine and tha he's just a curious person as he has a lot of friends tha are girls and he has went with them shopping so anyway that was that but I have a boyfriend and im very loyal to him and my cousin hasn't ever asked me anything like that again but it's playing on my mind have I don't something wrong by talking about my sex life with my cousin ?