Don't beg, it's extremely unattractive. I see no reason for you not to bring the subject up. If your relationship is good then it should be able to stand the test of talking about intimacy. You might be pleasantly surprised, and she may be wanting to talk about it as well. Isnt it better to have things out in the open and know once and for all where you stand.
And as for you comment about sex just happening. Yes it does a lot of the time, and most of the time it shouldn't have. I think if more people discussed it before just jumping into bed together it would save a hell of a lot of grief.