Should I worry?

So, first off, my period is always every 30 days. Well within the past 2 months, I started a new weight medication called Saxenda (It works similar to Insulin) and have lost 15 lbs. My period was scheduled to come May 7th and it didn’t. I usually don’t use protection (yes I know I should) but I’m always very careful, and he always pulls out before. I also always track my fertile window and am extra careful during that time. Yesterday May 12th, I took a pregnancy test when I returned home. At first it was negative, and I was relieved. But then after maybe 7 hours later I rechecked, and it was faintly positive (note that it was MANY hours later) I started panicking (but kinda happy to know that I could’ve gotten pregnant bc I deal with ovarian cysts) and bought 3 different brand pregnancy test, and they all came back negative (checked many hours later and still negative). Then I woke up today, and I have blood. It’s not red but it’s a brownish red. Sorry TMI. I am concerned but has this happened to anyone? I deal with ovarian cysts often and my doctor thinks I may have PCOS. I will take another test in a couple of days then go see my doctor.