Frequent Urge to Urinate!

I'm 22 weeks now with my first baby. Lately I've been experencing the constant urge to urinate. I know pregnant women pee a lot, but this seems really excessive. I can't get any relief from it. Most of the time I only get a few drops out, yet the feeling persists. I went to a regular practitioner over the weekend and had a urinalysis and it came back negative for a UTI. It's getting so bad that I can hardly function at work. I'm just wondering if anyone else is experiencing the same symptoms. Is this just what it's like to be at this stage of pregnancy? If so this is just unbearable!