Period 5 days early or implantation bleeding?

G.

Came off the pill in March after being on the pill for 16 years. My period came back like clockwork, which was a relief. Had two totally normal periods in the last two months, lasting 5 days each and perfectly on time.

This was my 2nd month TTC. Had mild cramps through whole cycle. Had sex with my husband 6 of 7 days of fertile days, and dollar store test confirmed ovulation last week on May 16. On May 22 and 23, had some pink spotting and I thought it could be implantation bleeding. Took an HPT this morning and it's negative (still a bit early to test.) By this afternoon, (8 DPO) I had heavier bleeding.

I think it's my period arriving 5 days early, but less cramps than usual and a bit lighter. I am under some stress at work but it was just a bit unexpected. Any chance it could still be implantation bleeding or more likely to be AF?