Sorry for the long read but I need to know what is wrong with me as nobody including the doctor seems to know :(

For a while now I've been suffering with obsessive thoughts.
It all started when I suffered a severe amount of guilt over something really silly. Anyway, I got over that and started to feel better. Until the feelings started to come back, but for no apparent reason. I put this down to anxiety and so did my GP. With the anxiety came a high level of stress because of this I dropped out of college, stopped enjoying the things that I used to enjoy and felt like I did not know myself. The anxiety got so severe that it affected my stomach, thinking and sleep patterns.
One day, out of complete NOWHERE I started to freak out thinking that I may turn into a lesbian... at first this thought wasn't that time consuming... Then all of a sudden it had this crippling affect that left me not wanting to leave the house other than to spend time with my boyfriend. I sort of new that I wasn't a lesbian, but was still worried about it anyway. It was like deep down I knew that I was straight but I just couldn't shake the thought. I thought about this all day everyday, I had no rest from it... it just completely took over. I would think silly things like 'If I dye my hair, I am a lesbian' which logically I know would not make sense, but I still believed it. After a while this thought dimmed down a bit and I learnt ways of coping with it a bit better. But I would (and still do) avoid certain programmes, music, activities, talking to certain people, because I knew that this would trigger off a thought.

After a while, the thought switched from thinking 'what if im a lesbian?' to 'what if i'm a peadophile?' this one was definitely the worst. It turned my stomach, I felt sick all the time, I hated myself... Again, even though I knew that I wasnt actually a peadophile, I was still worried and my mind still seemed to argue with me. This went on for a while and just like the last thought caused me to avoid certain things, children, films, reading. I even thought that wearing a low cut top would make me a peadophile. It was HORRIBLE. I also got intrusive images and not just thoughts with this one, It was one of the WORST things i've ever been through. It was horrible and at the time I felt so ashamed and disgusted with myself, I just wanted to die. The more I tried to block it out, the more it attacked me.

Then, it turned to my boyfriend (who is and has been for over a year my absolute world) I've tried explaining all of this to him and although it is wearing him out, he is very supportive. I keep questioning my love for him, weather I should be with him, what if I want to be single, what if i'm pretending, what if i've lost feeling. Now I know that these thoughts are not real because now and again I have a sudden sense of reality and I know that I love him. But at the time of the doubt it seems so real, I cry every single night, I feel like I don't want to be myself anymore. I end up taking things out on him, picking at our relationship as if it is his fault (which I know it is not). I don't feel I can cope much longer with these thoughts, I just want to be happy with him again. It's killing both of us and I have no idea what to do. I've thought that perhaps ending the relationship would be better for him, but I just can't do it... I love him to much. Sometimes I think that i'd be better off dead, as then I would be peaceful. I just want to sleep all the time, I don't want to be awake at all.

I just want answers, why am I like this? is it OCD? or am I just hopeless.
Any help or advice would be really appreciated :(
Thank you.