With your symptoms coming and going it sounds like baby position more than a uti. I always felt like I had to pee that late with DS. He'd also sit in ways that would really hurt and I'd have to change positions or sit down to make him move. Uti symptoms wouldn't disappear- they'd get worse. And if you have an asymptotic uti (meaning no symptoms but your urine tests positive for infection) then you shouldnt treat it anyway (according to my infectious disease nurse mother).
I also did a quick google search and most sites said a lot of women will get a positive and not to worry unless you are having symptoms. So I wouldnt worry unless your symptoms get consistent.
Meg, Momma to Joey (Feb 2010)