OBGYN?

Anyway, I will be turning 18 in April and I want to go see an OBGYN. I'm not sexually active and I've only sex once ( last July of 2015). I think I'm just being a bit over cautious, I just want to know if everything is OKAY down there. I don't want to go with my Mom cuz then she'll start asking unnecessary questions. So my question is... How old do you have to be to be able to go to an OBGYN alone? Is it a good idea to go alone? Are there any fees involved? Please help.