So, I've been having sex with my boyfriend for about 4 months now and I've never orgasmed, or at least I don't think I have. But it's not like the sex isn't good, it's great like really great. But, when we're having sex sometimes I start shaking a little and get this feeling that I can't really explain in my stomach.. But it doesn't feel like anything is coming out down there like cum or anything.. I just want some help what may be going on?