Hey, I am with an asian girl as well and I noticed the same thing. I felt something more clearly to be like it was in the shape of a tiny volcano the size of my index finger, but I felt no bulb inside (it was too tight to fit my finger completely into). I was to understand that if i were to touch a cervix, that it would hurt a girl badly, but my baby liked it a lot when I touched her there. Also, he vulva isn't really small but rather this was located on a very low vaginal wall towards her spine, and it seemed to be in a protected area folded towards her spine as well, while there was more room for my penis to fit upwards into her, and she indicated that ideally she would want me to be just a little bit bigger to hit the really really deep spot (she says that I reach really deep already, but apparently there's still room for more).
She was on her period when this happened, as she had said that she was always horniest before and during her period. As a side issue I also have to ask about some danger that might be there regarding this, because her vulva does this huge gulping action when she has a strong orgasmic contraction that sucks in air and then squeezes it out. I searched for some answers to whether or not the possibility of an air embolism forming was more likely to form during her period but couldn't find anything. I know that it's rare and all for that to happen in the first place, but there are some people out there putting a big stupid scare over it and it seems impractical with how often a vulva will do things like this during sex and even the fact of there being a lot of women who queef after sex. Information of period sex online doesn't seem to cover this possibility of a greater likelihood of an air embolism so I hope that someone here can clarify that for me.