NSFW:

I made you this, cause I thought, if I was doing it, I would have lowered the star a bit, cause right now it's sort of drawing you into her pubic mound, and the whole vaginal tunnel / vortex thing sits a bit lower on the underside of the hips.

Reference is usually helpful, so is doing a lot of figure drawing.

When you first do nudes and stuff, It's kind of difficult, because you maybe know in your head like roughly what is what, and where, but when you paint it out, it can be a bit different.

You can kind of see the woman with her hips angled so her legs are a bit up. The opening to the vortex on your character is sort of around where the pubic hair grows. Pubic mound. By lowering it, toward the opening, you can draw people 'INTO THE VAGINA!' -- and it will give you a chance to really draw out some more forms.

This is kind of crazy, but it will help you see what I'm talking about:

Super high definition -- so ultra high, you can see the texture of the skin.

Labia are sort of difficult. A lot of new artists just do like a single line or something, so don't be like taking this the wrong way or nothing. I'd just recommend using a bit more reference next time.

I'll leave you at that, maybe it will be helpful.

Best of luck with your work.