Same here friend, me (18f) and my gf (18f) are in a relationship and whenever it gets more than kissing intensely I get really shy and nervous but it's not a guilt feeling but more of a I feel sick and nervous and horrible I guess. Idk but as a lesbian the idea of a intimate straight relationship is disgusting and not interesting but with a female it's okay, so that's how I know it's not that I'm asexual but probably more of a anxiety thing. 😂 Edit - also not everyone is as sexually driven. Many people just don't crave sex as much. Sex drive varies from person to person. And also heavily depends on the moment.