Why aren’t my nipples sensitive?

I’ve tried playing with my nipples but they just aren’t sensitive, like at all. Even before or during my period. I’ve tried pinching, rubbing, everything! I just don’t feel anything, and never have(I’m 14 btw) even when I first started having boobs they’ve never felt sensitive. Is that just me? I saw a post where someone said they could orgasm from nipple simulation and I was like what?! How?! I want that! Why am I like this???