TTC after blighted ovum, late period.

Tina
November 2016 my husband and I found out we were expecting. Our first appointment our pregnancy was diagnosed as a blighted ovum. I had a medical miscarriage starting in December and finally stopped bleeding in January. I had a normal period February 25th through the 1st and then had another normal period March 27th through the 1st. Now, April has gone by and I'm 6 days late on my period, 15 dpo. I've taken a blue dye test and it was faint positive. I've also taken 2 pink dye tests and those have looked negative. Idk what is going on. How long should I wait to call my doctor and see what's going on?