Thought I had a UTI...?

Felt pain and burning all day Saturday and yes, urges to urinate and most times very little came out. Took a UTI test with 1st urine Sunday morning, that showed Positive for Nitrates and Negative for Protein. Then yesterday, Monday, I bought another set of test strips and each time they showed WBC positive in urine throughout the day but no nitrates. I went to the doctor and she prescribed Ciprofloxacin HCL 500 mg Taran 1 tablet twice daily. I took 1 last night before dinner with a yogurt "drink". This morning I have no symptoms and sampled with 1st urine of the morning with the UTI test (2nd stick from the pack Sunday), both indicators came back negative for Nitrite or Protein. I did go ahead and take the morning does of the antibiotic. Did it go away that fast? Is the lab that took a urine sample yesterday going to find anything in the cultures they do?