Am I pregnant or over thinking?

I am on birth control, and just had my last active pill today, but I switched pill kinds last week, and stopped the old ones mid pack and started new ones right where I left off. I haven't missed any pills. But last week I was paranoid so I took 2 first response tests and a clear blue, first response ones looked like they had one faint line, very very, or an evap line. But clear blue was totally negative. So the next day I took 2 more first response and they were negative. This week on Tuesday and Wednesday I had a brown discharge, people said it was old blood. Then the next day after that I wiped and had a little light colored blood with brown blood.. Which would be day 28 of my cycle if I wasn't on birth control, thought my period was starting, now nothing. Is this normal or what? I thought implantation would have come earlier than this, maybe bc side effects?