I think you'd be rushing it to try and get a girl who's only ever kissed to having sex in a week. The fact that she's only ever kissed indicates that she's not ready to do anything more anyway.
Perhaps it would help to go back to thinking about the old 'bases' analogy. Kissing first base, Breasts second base, heavy petting (hate that term) third base and sex is the home run. Most girls take their time building up to sex, gradually working through the bases and getting more comfortable with the whole sex thing. Unless she's desperately horny and begging you for sex, I think you'll find that she's also one who will gradually work through the bases. When I talk about gradually working through the bases, I'm talking months - or even a year or two. But certainly not a week.
Also, first time sex is usually pretty clumsy and awkward...and you won't have time to hone your skills together. Do you want her memory of sex with you to be like that?
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.