chances of being pregnant in this situation?

So, I’ve been on the pill for a year. Never missed a pill, only “late” on an occasion (MAYBE an hour and a half at latest, usually on time). I had sex without a condom March 23rd. He did not end up ejaculating or getting close to ejaculating at all while he was inside of me. It was a couple strokes for like a minute and then out. I finished him off with my hand. That next week I got my withdrawal bleed which was normal and lasted about 5 does like it usually does. Haven’t had sex since that withdrawal bleed. This month I have been taking my pills like usual and never missing but around the very end of my second week I started to experience some breakthrough bleeding that I notice when I wipe sometimes. It is brown and very light. It looks familiar to what I’ve gotten before when my withdrawal bleeding is about to start but I’ve never experienced it this early (taking my first sugar pill this sunday). Should I be concerned? I would say I have been under some stress due to doing university online due to the coronavirus but should I be concerned about pregnancy? I am freaking myself out a little bit and I guess it’s just because I have time to sit inside and think.