My urine test is positive for leukocytes and negative for nitrates, is that even possible fot uti?

Yes: Leukocytes mean your body is making an inflammatory reaction. A positive nitrite test indicates a gram negative bacteria is present. You could have a bladder infection with a bacteria which does not convert nitrates to nitrites. An example is enterococci, which can cause an infection, cause white cells, yet not change the nitrites portion of the dipstick. Microscopic exam and culture are important.