Please help me figure this out!

Im a 26 year old female and there is definitely something going on with me and I need help figuring out what it is. I've had an average amount sexual partners in the past and kind of react "normally" to intercourse by reaching orgasm during sex. However I experience the lack of excitement during sex that leads to orgasm if that makes sense. Its like the mental connection that creates the build up leading the orgasm has never existed, with any of my partners. I'm attracted to the opposite sex, I have the desire to have sex and be in romantic relationships...Its just the mental aspect of it all screwed up. This is a big issue for me because it makes sex not as enjoyable for me or anyone else involved, so at this point I figure why even bother pursuing a relationship. Is there a chemical imbalance, hormonal issue...mental disorder. I'm dying to know so I can try to work on this.