Hey Big, I think you know the answer to your original question, being that you have gone on consecutive dates with her.
My question is, have you met the parents? If so, then impressions? Sorry if you posted that already, after a couple of pages of hit it, I skipped to the end to see if there where any more updates.
Lastly, just ask yourself these questions:
1. Is she of legal age? Yes/No
2. Are you looking for long term commitment? Yes/No
If you answer yes to question 2, then have sex with her, but let her make the moves, if you are good enough to read her queues, then make them yourself. But keep yourself emotionally detached, while still playing like you want to keep her. If she seems to want long term as well, then tell her you are looking for the same, and you should really act naturally. Marriages are not about the honeymoon feeling, its about being able to live with the worst the other person has to offer, and still being able to look at yourself and be happy with your life, and know you still love that person.
If you answered no for question two, still have the sex.
And no I didn't plan to write all this, it just came out. Good luck.