Lack of Vaginal Sensitivity

I'm in my mid 30s and I went 7 years without sex. I started dating my man over a year ago and we just started having sex a few months ago.

I'm having a really hard time feeling his penis inside of me. It's average size, I think. It's definitely not huge, but it's not tiny. I really only feel him when he hits my g-spot and only in a few different positions. He's amazing at giving me pleasure in other ways. I have a lot of sensitivity on my outer lips and clit. So no complaints, he really he cares about my sexual pleasure. I'm just curious, how do I regain feeling inside my vagina? Tips? Topical? Vitamins? Specific exercises?