Thoughts?

Hey everyone, so, I went in for some routine blood work and they ended up finding some bacteria in my urine sample... MASU... My doctor put me on an eight-day course of antibiotics, but before I even started those pills, I had already gone in for a urine culture. The results came back completely sterile. When I went back to talk to my doctor, she just told me everything was fine and that I shouldn't worry about it.
I guess I'm just confused... why bother with a whole round of antibiotics if the culture came back clear?
Do you guys think it’s actually okay if the culture shows nothing?
Thanks so much for any insight..
Oh, by the way, all my other labs were perfect, except for low iron levels, but since I just finished my period, she said that was totally normal..

Did you start taking those antibiotics before the doctor had a chance to review your lab results?

Yeah, that’s right. I went to see my doctor with my blood work results, and she prescribed some antibiotics—three times a day, you know? I took them that same day, and then by the following morning, I was already at the clinic getting a urinalysis done.