just in-vagina numbness

I can't really feel the opening of my vagina. I touch it and I don't feel anything, i can feel sex and I enjoy sex but I feel it on the inside. I also have feeling on everything in the outside, just not the opening. The opening is basically numb. It's always been this way and I don't have any kids. Am I the only one? I've been checked for everything and I'm fine but I didn't even think to ask the gyno about it because I don't ever really think about it.