My boyfriend wants to have sex more, but I just can't get into the mood, but I want to.

I used to be that turned on girlfriend I think all guys dream about. I wanted to rip off his clothes every time I saw him. When we were first together, I wanted to have sex minimum of twice a day. Sex was not enough to bind us together because I was young. We have had a rough relationship till now. I am five years younger than he is and I thought as a freshman I should be dating around and finding who I was and who I wanted to be with. I thought he was ready to settle and I shouldn't "settle." So I kept talking to other guys, just as friends, but then I would realize I was interested. I used to not have sex as much right before we would break up from me wanting to be single or try a relationship with someone else or just cause of a fight.

So, of course now he thinks I have found another guy or just am not interested anymore. I love this man to death. I want to marry him and spend my lifetime with him. I want to have sex with him and make him happy, but I am just not in the mood. I don't know what my problem is. 

I know that in the beginning of our relationship I didn't have much confidence. I had been used at a young age by a few guys that just thought it was all good. I have also been raped by a friend who thought I was down, but I couldn't speak because of being so intoxicated. I definitely have issues to letting someone get close to me. It's weird I could have sex when I felt like I was in control, but I when I don't feel that way I run and close off. 

We still have sex 1-4 times a week, but it is very inconsistent due to my schooling and his work. We are both very stressed individuals because of the amount of work we do. I enjoy have sex with him when we do. I orgasm like no one I have ever heard. I want to have sex more, but I can't get into the mood as much. I haven't been working out as much and I know I don't look like I used to, which might be causing me to feel uncomfortable. More than anything else, is that my vagina has been smelling. I don't know why, and have been hoping that my periods will take care of it. I keep getting a little discouraged when we do have sex because I feel disgusting. He says I'm the most beautiful thing in his life and doesn't care about the smell or me not working out. But I know that before I was so much more. 

Is this just a mental block or a physical or even a deeper meaning? What should I do? I don't want him to masturbate  which I found out he does now. He never used to. I want him to have sex with me and not his hand. HELP ME!!