I am NOT trying to conceive.
So, I missed my last period, which was supposed to start around April 25th. I haven't had sex since April 13th.
About 2 days ago, I started noticing spotting on my pantyliner. It was very very light brown. Gradually, the bleeding has gotten heavier, but not heavy enough to have to wear a pad. The spots are brownish red, dark in the center and lighter at the edges.

I also had 2 cases of UTI a few weeks prior so I was put on antibiotics each time..not sure if this is somehow relevant.

Is this implantation bleeding? Because I know implantation bleeding is supposed to occur BEFORE your menstrual period, but for me, it happened a week after.

Just to clarify, the spots are not small drops. And the blood flow is similar to that of the last few days of a regular period.