Freaked out that I'm gonna get a kidney infection?

Last week, about 5 days after having sex where I forgot to pee afterward, I noticed slight burning while peeing. It really only lasted a day or two, I went to the doctor, she said I didn't have a UTI, and it went away. Two days ago it came back. It really only burns towards the end of my pee, I don't have the urge to frequently go, no abdominal pain/fever, etc. I've only bren slightly uncomfortable for the past hour or so as it feels a bit burny down there. Otherwise I'm good. I saw a doctor again today and he didn't seem concerned at all, felt around my abdomen and tested my pee. I had leukocytes but no nitrite and SLIGHT blood on the test stick, but he didn't prescribe me any meds or antibiotics. Test results come back Monday, and I have a gyno appt Monday as well.. but I'm leaving for a short vacation tomorrow morning and coming home Sunday night and I'm scared that if it is a UTI with no antibiotics it may turn into kidney infection and ruin my trip or something. Should I be worried?