Implantation bleeding?

I’ve been pregnant 4 times and never had implantation bleeding with any of my pregnancies.

The last 2 pregnancies were this year and both ended in miscarriage; one at 12w5d in April and the other at 6w2d in June.

My periods cycles since my last miscarriage have been 6.5 weeks, then 5.5 weeks. It’s been 4 weeks 3 days since my last period.

On Saturday, Sunday and Monday I felt mild cramping like I was going to get my period. Tuesday at 2 am I went to the bathroom and there was pink blood on the toilet paper so I assumed I was getting my period. When I got back up at 6 am and went to the bathroom there was very light pink mixed with slightly sticky discharge on the toilet paper and there has been nothing since then. Could this be implantation bleeding? I took a test yesterday afternoon ( I know fmu is best but I was curious) and it was negative. If it was implantation bleeding when should I test again?