I’m having trouble having sex with my bf

I love my boyfriend. But when he asks me to have sex with him. I get annoyed, We have great sex and I’m really attracted to him. I know he gets upset when I don’t want to have sex or engage in for play. It makes me feel very guilty and like I’m a terrible girlfriend for not wanting to have sex with my boyfriend every chance I get. When I was young I was sexually assaulted and there’s days when I get sad over it and don’t want to have sex. He just doesn’t understand me when I say it’s not his fault. I never really told anyone what happened to me. It’s something I’ve kept to myself because I’m afraid of people accusing me me of lying or judging me. It’s just I don’t know what to do and how to snap out of this sadness I have. I tried to seek help from a doctor but he said I’m depressed because of the fact I’m overweight. I didn’t go back to that doctor so I wasn’t able to get the proper mental help I needed. I really love my boyfriend and I don’t want something as dumb as sex to tear us apart. I just want him to understand where I come from. And for him to get what I went through and why it holds me back for intimacy. Please help! 😢