OK. Zack, yes, I think you have been a little graphic here. Doesn't matter whether this is a cousin or not, it's more than most people like to know about. Next time just keep it to the bare bones - she likes you, she lets you touch/kiss her intimately. Doesn't have to be any more descriptive than that, babe.
Now to the problem in hand. Since you and she already seem very close, why not talk to her about you feel. She may feel the same, she may not. If she doesn't, then you should at least be able to work things out and not fall out over it. If she does, well that's great.
For centuries, cousins from all cultures have married. Some will tell you it's wrong, because that's how they've been brought up, and I guess that's why you're asking the question in the first place. Others (like me and Le Chat) are able to be a little more open-minded about things. If you continue in this relationship, then as long it's what you both want, and as long as it's legal where you live, it has nothing to do with anyone else, and good luck to both of you.