Confused

Wondering if anyone has experience this. My periods are normally like clockwork and come on time each month. This month I’ve been really spotty. My headaches have been crazy this week and I’ve been feeling sick. I got slight period cramps the day before I should have come on but didn’t come on for another 3 days (so 3 days late). When it did come, it had been very light and only lasted 2 days, I normally bleed 4 days. I did take a pregnancy test on my first and second day of a missed period but both said negative. I feel stupid for even asking but could I still be pregnant? I’m guessing not. Has anyone had slightly heavier (to what the internet says) implantation bleeding that lasted around a day/2 days? Thanks