Weird period? Implantation?

Last month (September)I was put on birth control while going through infertility testing- after some thought and lots of prayers we decided to not do further testing and just give it a rest. I stopped the birth control two days before it was due to stop- had spotting the next day and then a full on regular period for 4 days. Fast forward to this month- I was due to start my period yesterday- however on Wednesday I had some mild cramping for about 30 min and then spotting- this spotting has continued on and off since. Normally on my first day of my period I have terrible cramps and pretty heavy bleeding for 3-4 days. This hasn’t even been enough to wear more than a panty liner. I took a hpt this morning and got a bfn. Any ideas what is going on? Have any of y’all had this and got a bfp?