why can't I feel his penis inside me

Every time me and my boyfriend have sex I can't feel his penis inside me, he's not small so that's not a problem. I don't seem to cum and I just don't feel him we've tried different positions and it just doesn't help. Any ideas???
UPDATE:-
I'm not on any birth control as ttc baby number two, I had my last son 12 yrs ago
He is not small at all is say around 7 inches 
I feel him hit my cervix a lot of the time but don't feel him anywhere else 
Some not not sure what else we could try so I can feel him, I've never came from penetration and I really want to try to