PLEASE ANSWER?!?!! URGENT!!

Okay so I take my birth control religiously. I’ve been on for about 3-4 months and on Feb 21st, my boyfriend and I had unprotected sex. That same night, I missed my last active pill of that pack. The next day when I remembered, I took that missed pill and at 7 that night, I immediately started a new pack to be on the safe side and skipped my break week. I waited until 9 days into the new pack just to be extra safe to have sex again. I’ve taken the new pack all on time and I’m 2 days away from my break week. 2 days ago, I had this on my underwear as well as a small amount of gooey brown discharge. I keep seeing people say it can be implantation bleeding and I’m super scared is this normal and just breakthrough bleeding oxidized blood? I don’t want to be pregnant and I thought I took all the possible precautions from missing my pill.