Can I be pregnant?

Hi, I'm a 22-year-old girl, and I'm wondering if it's possible that I'm pregnant? I know there's always a chance, but I wanted to hear your opinions anyway.

First of all, let me say that due to a pretty hectic period, I missed a pill in my pack once. It started a small while before my expected period (EP) that (sorry for the details) when I have sex with my boyfriend, everything feels so tight and constricted. This is actually nice, but I've never experienced it before my EP that it felt so intense and that I was so tired afterwards.

I tested before my EP (a bit too early) and it was negative.

Now, a day before my EP, I started getting really nauseous every morning and around 3 PM. Not just a little bit (since I have reflux, I know what a little bit of nausea feels like), but really so nauseous that at times I just want to panic-run to the toilet because I think I'm going to throw up (haven't had to yet). I also get a headache and stomachache during those moments.

The pain in my stomach and breasts is there, but usually vague—a heavy feeling in my breasts, tightness, or weird little cramps in my stomach.

On the day of my EP, I got brown discharge and very little of it. I thought this would be the start of my period. Day 2 was the same but with a mucus plug, still noticeably little, a bit on my pad, and when wiping, just a small vague trace. Now it's day 3 and it's still the same. Since yesterday, I had to restart my pills again (because of the missed pills) since I normally restart every Thursday. Now I don't know anything anymore... did my period come or not...

Any tips, or experiences that sound similar?
Anyway, I'll test again if this persists.