Fasting numbers

I feel crazy but I have noticed the nights I eat more carbs, my fasting number is in the 70's and the less carbs I eat the higher my fasting number tends to be. For instance, I ate a medium onion ring from bk before bed a few nights ago, not the best choice, I know and my fasting number next day was 76! If I eat yogurt, wheat toast with PB, almond milk, hard boiled eggs, etc my numbers show 80's or low 90's. Has anyone else experienced this? My after meal numbers are always below 110. One day, I experimented and I ate a big mac meal with a medium fry and my 1 hour post meal number was 112. It just seems the more carbs I eat, the better my sugar including my fasting number and the less carbs I eat, the higher my numbers. My obgyn diagnosed me as gestional diabetic due to a A1C of 5.7 and bc I failed my 1 hour.