Alright, so heres the deal. I'm 18, and a virgin. My new girlfriend knows this and is fine with it (shes only been with 2 guys herself). The problem is, that everytime we get to the point where we're about to have sex, I totally lose my erection. I become extremely nervous, i.E. My heart starts beating really fast and I almost feel sick. This has happened like 5 times now and it's really starting to get to me. I want to lose my virginity to this girl but I literally can't seem to be able to do it. I have no problem maintaining an erection when she gives me oral at all. On a side note, it seems that my libido is really low compared to the typical 18 year old guy. I just don't seem to want it that much, and i've never had a wet dream in my entire life. I've never actually wanted sex with any girl that i've been with now that I think of it. I really like this girl, so it's not a lack of interest in her, it's a lack of interest in sex in general. This is starting to put stress on the relationship, and I really don't know who to ask about this...A doctor? A psychologist? Any insight into this would be greatly appreciated, as i'm realy not sure if it's a phisical problem or a mental thing.