2 chemical losses in 4 months

I am a 35 yo who is ttc #2. We have been trying for a year and we have had zero success. In july i was diagnosed with diabetes and am taking metformin 1000mg bid. Since then ive had 2 chemical losses. One in.october and 1 in January. I am wondering if its low progesterone because my sugars are within range (fasting can be 120 sometimes). What were peoples signs of low progesterone or was i unlucky enough to just have 2 abnormal embryos in a row? Eta i have a ob appointment at the end of the month