It's okay to ask her, but you really need to make sure she understands what she's getting into. Age 12 puts her at what... 6th/7th grade? Most "sex ed" classes by then have barely covered that part of your anatomy, if they've been offered in the school at all.
In my opinion, middle school is way too young to be having sex. In fact, I think even up to freshman year is a little too young. Generally speaking, I think it would be safe to say that most girls are not ready for sex at that age. Speaking from my own experience, even when I was 15, I wasn't ready for sure. Between 15 and 16, I probably would have said no if I were asked outright, but (despite being slightly uncomfortable) allowed it if my boyfriend at the time initiated it physically.
My (current) boyfriend waited until I was comfortable initiating it myself (17 years old, and 5 months into a loving, supportive relationship), and I really appreciate that. I'm not going to pretend we didn't mess around before then, but I think having actual intercourse is a delicate and emotional decision for a girl. Again, I can really only speak for myself, but I doubt anyone truly forgets their first time (unless they're drunk or something, but I doubt anyone would forget THAT either). It's important that she be able to look back on it without any regrets.
That said, I can understand how you feel, being a bit older than her and all... I think it would be best for both of you if you let the intercourse wait, and trying other ways of pleasing each other. Of course, it should always be a mutual decision, that BOTH of you are completely comfortable with (AND FULLY UNDERSTAND), no matter what you decide. smile
