Really need some advice please!

Hi ladies,
​So i was diagnosed with gestational diabetes at around 30 weeks. Ive managed to get my after meal numbers under control through diet and exercise, however my fasting numbers have been high. I began taking metformin about two weeks ago and my fasting levels have consistently been under 6. Apparently thts not good enough for my docs and they want them under 5.3. Im taking 1000mg of metformin after dinner n my fasting numbers r always in the 5 range. I dont want to take insulin...how can i convince my doc?
​They told me to start taking insulin about 10 days ago bt i havent. A couple times my sugar level two hours after meal was 4.6 and i felt horrible!! Very lightheaded and nauseous and shaky! I can only imagine how much worse id feel with fasting levels below 5.3! 
​I need some advice on how to convince my doctors please! They r super rude and have basically been trying to force me into taking insulin..and i am hating the feeling of having no say in the matter! Its MY body and i really dont think insulin would be good for me..i jst need to kno how to convince my docs!
​Please respond!