Why I dont feel my G spot?

Probably there's no problem.

The so-called G-spot (aka the back of the clitoris) is easily accessible for some women, but for a very large fraction of the population it isn't, and vaginal orgasm without clitoral stimulation is really just not going to happen. You can, to a certain extent, train yourself to orgasm from the more indirect sensations provided by internal stimulation... it's much the same process as when you discovered your clitoris and just takes a lot of practice with a very patient partner or with a sex toy. But it's not a sign that anything's wrong with you if it isn't working.

I have the exact same problem! My boyfriend tries, but it ends up getting too rough and it hurts me. So I'm not sure if its only a thing some women can do or if its just us two that can't seem to get it right. You're not alone anyway, so don't worry about that haha