Heavy implantation bleeding or abnormal period?

My cycle is extremely regular. Never more than 29 days and I usually have mild symptoms (sore breast, for a day or two, headache the day before).

My period is also extremely predictable. I have 1 moderate day, 1 heavy day (often with clots) and then another moderate day with a 4th day of just spotting...

However this time was different. My breast were sore for a solid week, headache for the whole week, and pretty fatigued. My period was 2 days last and what followed was so different than normal. My period only lasted a day and a half, light the first day (very little “red” mostly pink and brown) and spotting the second.

Is it even possible that is is implantation? I don’t want to take a test just to see another negative. Wondering if anyone has experienced anything like that and found out they were pregnant?