do you have a link to her profile?
ALOT of girls will do this, they will make you cum as quickly as possible and get you out the door to be free to meet someone else. read the reviews sections on here, there are plenty of nice girls who wont clock watch, and you'll get far more fun for your money.
as an unwritten rule half hours are a cum once affair with most ladies (despite what they write on their profiles), so its best to spend time enjoying foreplay and having extended fun at the beginning of your date.