Implantation Bleeding and Pregnancy Test

Okay, ladies I need a little advice/insight. I’m a mom of two, my youngest will be eighteen months on the 27th. I have not had my period in 27 months. {I’m nursing/weaning...} On the 9th I had what I thought was the start of my period, because I had been really crampy for a couple days prior - light bleeding, light red shade. That is the ONLY time I bled, so not my period. Could it be implantation bleeding? I’ve took tests on Saturday the 11th and 12th and they showed not pregnant. Should I test again? Could it have been implantation or just my body being confused? Thanks for the advice!