There's really no point waiting especially after becoming exclusive, unless she's not as committed as you might think. Another possibility is some fear or insecurity, like her parents judging or something even completely irrational. I don't think you should wait, I think you should get to the bottom of what's holding her back. Ask her what's holding her back. If you get nowhere with that, question her commitment by telling her it's going to happen anyways unless she has other plans. If she doesn't tell you what's really holding her back or just complies, then she probably had other plans meaning you dump her. Either way this will solve your problem.
I met the parents of my girlfriend before we got exclusive, was never an issue. I had pretty much made up my mind anyways, I was ready to commit so I saw no reason to delay the inevitable.