@Rogue0,
I don't think it's a major problem but I do suggest being respectful (which I would suggest to anyone) and maybe allow her to set a lot of the timetable, seeing as she is under 18.
16 and 19 can seem like a huge gap and kissing is fine, but when it comes to sex you should cool it as she is still a minor. So have fun together! But keep it light.