Diabetes after Gestational diabetes.

Hello, I had gestational diabetes with fasting sugar ranging between 130-160 from 6th month untill delivery. Took insulin for 1 1/2  month in last month of pregnancy. Before pregnancy also, my blood sugar levels were 120-130. I had 3 failed iui and one IVF which resulted in successful pregnancy. Delivery happened 3 1/2 months ago. After pregnancy also my blood sugar levels are around 130-140. I have stopped my insulin after delivery. I m still breastfeeding my new born baby girl. Yesterday afternoon suddenly i had drop in my bp. It felt like room spinning while i was lying on bed. Was not able to keep my eyes open. Was sweating too much. And finally vomited whatever i ate in lunch. Is this due to high blood sugars? When i checked my bp, it was 80/58.