After a search spanning sixty years of medical articles, The Journal of Sexual Medicine cannot confirm that a female G-spot exists. Finally, you can stop beating yourself up over missing those anatomy classes in middle school.
The search looked for vital terms like "G-spot, Grafenberg spot, vaginal innervation, female orgasm, female erogenous zone, and female ejaculation” in articles from 1950 to 2011, and examined clinical trials, meeting abstracts, case reports, and review articles, but failed to locate a unique entity that causes sexual pleasure, other than the clitoris. Surveys, pathologic specimens, various imaging modalities, and biochemical markers yielded the same result: we're not totally sure what's going on down there.
As if vaginas aren't confusing enough, the surveys gave results that a large amount of women believe the G-spot exists, though they couldn't tell you where it exactly is. This doesn't give too much hope to awkward couples the world over; when you're fumbling around down there, desperately trying to give any kind of sexual gratification, the last thing you want to hear when you ask if it feels good is: "Uh, maybe?"
Well, you heard it yourself: science confirms the vagina is a labyrinth. Granted, there's a lot more to be learned about the human body and how pleasure works. Maybe in another sixty years, we'll figure it out. Man, the future's going to kick ass.