Bladder Infection or UTI and Pregnancy?

So this is my story... I am 19 and I have been having pregnancy like symptoms for about a week and a half. I have been nauseous, tired, bloated, enhanced smelling, mild ache and some cramping, frequent urination, hungry all the time, darkening around my nipples, and pain in my breast, and bluish veins on my breasts. No bleeding or severe pain. My periods are so irregular I wouldn't know when to check, but if I am I would only be about 4 and a half weeks. I took 2 tests a couple days ago and there were negative. I went to the hospital last night to find out what was going on because I thought it might be ectopic or something like that, but they said the urine pregnancy test was negative (I figured it would be.), so the first nurse came in and said you have a bladder infection. The nurse who discharged me said I have a UTI... I have no pain when I pee, consistent flow every time, no pressure to pee. So my question is could I be pregnant and still have a infection because I don't know why my breasts would be changing from an infection? Help please!

Also does anyone know if I should wait on starting the antibiotic, it is called bactrim? I also have never had a UTI or Bladder infection before.