I have been having unprotected sex since May.

My period comes like clockwork every month on the 26th, but the last one was different. I was feeling sick, had sore breasts and nipples  I took a test but it was negative. Then a day later, I started bleeding, that was June 23rd. 3 days early, which never happens. it was just light spotting and then I got a medium flow that was reddish brown and then got lighter but only lasted 3-4 days, which isn’t normal for me. Usually, my periods are extremely heavy and last 7-10 days but this one was different. On Tuesday, July 6th, I started spotting very little and then it stopped. I’ve also been nauseous and getting headaches. I took a test but it was negative again. I currently have a UTI and wondered if it is affecting my pregnancy test or could it be too early to tell?

If I am pregnant, I would only be about 4 weeks along… Any advice?