Spotting 3 days bf AF

I had a miscarriage in early February then started TTC in April. Ever since then I have been getting light spotting about 3-4 days before my period, then it stops, then the normal flow when predicted. This never used to happen. Each month I get excited hoping it’s implantation bleeding (timing is about right!) only to be even more disappointed when Aunt Flow shows up. My cramps have also been worse than usual. I have sent a similar message to my ob, but thought I’d see if anyone on here has had it happen as well. Thanks!