Is my attitude towards sex normal?

I am 20 years old and have been with my partner for two years. When we first got together we had what I would consider a relatively healthy sex life, despite spending our first year long distance. We would experiment to keep the spice going when we were both together and apart. He is the only partner who has been able to make me orgasm. However sex is something I struggle to participate in. It has now been nearly a year since we last had sex as I simply can't bring myself to do it. When I was 16 I was manipulated and coerced into a sexual relationship I didn't want to be in with a man 11 years my senior who was engaged. A year later I broke down and told his fiancee what had been happening as it was the only way I could figure out how to get him out of my life. I can't understand now how it happened, but it did and I will forever be ashamed and disgusted with myself for letting it. I think it is since then that I have had disgusting feelings associated with sex. The thought of doing it makes me feel clammy and nauseous. After doing it with my boyfriend in the past I would struggle to be near him after as I would feel too disgusting, dirty and guilty. My father died just over a year a go and since then my feelings about sex have become worse. I like to think that those who love us watch over us after they have passed and as such the idea that my dad is now able to see everything I do only further puts me off sex. Finally, my partner is the loveliest guy I know and I am so very lucky to have him. Unfortunately (and this is where my shallowness comes in, of which I am embarrassed) I am not hugely attracted to him. I love him dearly and he is my best friend, we have been through a lot together both as friends prior to our relationship and since. I never had a crush on him before we got together and there has never been much passion between us. He is receding and beginning to get a bald patch on his head which I struggle to accept (I know, how shallow!). Luckily he is tall and has a great hairdresser so for now it is not a pressing issue. Another thing is his penis. His foreskin does not retract and when we have had unprotected sex in the past I have gotten thrush afterwards. The only real treatment for this problem (as he has been to the doctor and tried other alternatives) is to get a circumcision which he is understandably opposed to. We occasionally have oral sex or foreplay in which we can orgasm however I still feel wrong after this too (but it would not be fair on my partner to not give him anything).I know my feelings and behaviour are not healthy, and I ashamed of my feelings towards my wonderful partner. I just feel so abnormal and confused. Is there anything I can do? Are these feelings normal?