Implantation, miscarriage or weird period?

Before I explain what happened this month, I feel like I should explain that my period is always consistent. I always have a heavy flow with severe cramps on the first 2 days of my period & then both the flow and cramps get milder. The duration of my period generally lasts 6 or 7 days, never any less. Sometimes the stomach cramps that accompany my period can actually be so painful that I faint.

This month, my period was late by 6 days and I started spotting. Very light bleeding that was only visible when wiped by toilet paper, nothing “dripping” (sorry, TMI). I had very mild stomach cramps, almost so mild that I was barely even aware they were there. I believed this was implantation bleeding and this continued for about 4 hours.

The cramps got more painful, however, still not how my normal period cramps would feel. Eventually, I went to the toilet as I felt nauseous. I could only have been sat on the toilet for a matter of minutes before I passed a blood clot, (attached photograph). Normally, in my period, I pass blood clots into my sanitary towel or tampon... but never anywhere near this size. This is the biggest clot I’ve ever seen. Could this have been a miscarriage before my pregnancy was even confirmed?

After the blood clot passed, the bleeding got a bit heavier. It still wasn’t like any of my “normal” periods. The flow was enough that I had to wear a sanitary pad but not enough that I had to change the pad regularly. I wore the same pad for the full day.

Today is now 2 days after the spotting first began and there’s no blood. I used a clearblue digital pregnancy test to test for pregnancy and got a “not pregnant” result.

Has anybody had any similar experiences, or advice? Could this be implantation bleeding? Is it too early for a pregnancy test to give a positive result? Or could this have been a miscarriage?

Please share your own similar stories and outcomes, & also any advice would be appreciated.

Feel free to ask any questions.