Sex can't change the size or shape of the vulva. Arousal causes some temprary swelling, but again, no permanent changes. Puberty, however, causes some changes, as does age, but in the latter case, they're very subtle.
Inner labia, peepers or no, are not disgusting. They're a normal part of your anatomy, just like the lips on your face or your earlobes.
Genitals aren't ugly. What it sounds like, actually, is that right now is a BAD time for you to be sexually active with a partner, because so long as you feel that way, it's only going to reinforce those feelings, rather than help them to subside. As well, if you're not willing to get sexual healthcare, you're playing russian roulette with your health being sexually active, and shame tends to increase risks.
So, what I'd suggest is this:
1) take a break from sexual partnership until you're much more okay with your body and everyone's genitals.
2) DO see a GYN. While you're there, ask about genitals, about what's normal and what's what.
3) ...and this is going to sound harsh, but: get over it. hating any part of your body isn't good for you or anyone, and it's especially silly when it's out of ignorance, or made worse by going into things you really don't feel ready for or comfortable with. While you're working on getting over it, go to the library. Pick up medical textboks and anatomy books and have a real look at what genitals look like. if you have, perhaps, any issues stemming from sexual trauma (like rape or molestation), get some help with those. If your body shame continues despite your efforts, seek out counseling.