Implantation bleeding or Late period?

I had sex on the 4th,10th,14th,16th,26th,30th and 31st of last month, my period was supposed to start (glow app start date) on the 30th of last month and end on the 3rd.

I started lightly bleeding on the 4th a dark rusty color, barely filled up a panty liner, and had mild cramping, today i’ve had light pink spotting and very random light cramping, not as much on the panty liner as yesterday.

I took two pregnancy tests so far, one on the 30th and one this morning. Both negative.

I’ve been moody, having some lower back pain, and my breasts are becoming sore feeling. Anything and everything irritates me, I also feel bloated.

Is it implantation bleeding or a small late period?