I have on occasion wondered whether I'm in this situation. I've had sex with many partners and can honestly say that only probably half a dozen have created any sort of sensation - and those who did - WOW.
I've wondered whether my nerve endings are deeper or something, or whether the majority of guys I've been with just have no idea that the need to find out what works for me. The ones who have created intense feeling haven't done anything different that I could tell, but they obviously do somehting differently. I've seen other women 'get off' with anyone and everyone they have sex with, so what' so different with me?
I have found that exploring my Gspot has helped a lot and I feel I'm becoming a bit more responsive. Having my hips tilted/lifted (pillow under my butt) certainly helps, and sex in doggy position is a winner.
The inside of the vagina isn't particularly sensitive. It can't be or pushing a baby out would be more torture than it already is lol But certain parts of it are - Gspot and down near the cervix for me. Experitment on your own with a dildo, one that you have room to move around. Relax and take note of any 'spots' that respond when you press against them with the tip of it.
I still don't know whether I'm just different to most women, but don't give up hope. I have had mindblowing sex despite most of the rest of it has been as if nothing at all was happening. Good luck.