Spotting followed by uterus twinges

Hi everyone, I’m hoping to see if anyone had implantation spotting (2 days) then at the very end of the spotting I started getting twinges in my uterus, like a mini muscle spasm that doesn’t hurt. It happens at least 3-7 times per day and only last up to 30 seconds. It’s happened every day for 8 days since the spotting ended. I’ve had 2-3 occurrences where it’s a more dull ache that slightly hurts but it only lasts a minute or so as well. Spotting happened exactly in day of expected AF and have not had any spotting/bleeding since. All pregnancy tests have been negative so far but the women in my family have naturally very low Hcg and have a hard time getting an HPC to turn positive when they really are pregnant.