I think there are 3 important things for you to do:
1. Find out ASAP what type you are. T1 or T2 or one of the variations in between.
2. This diagnosis will determine your action with the insulin. In my experience as not T1 is that the insulin increased my sugar levels that required more insulin that increased my sugar that required more insulin that...etc., etc. I also put on over 20 lbs in about 5 months.
3. Depending on the true diagnosis, research and decide on the most appropriate diet for your condition and for you. This site and forum will be invaluable for this. My solution was/is a low carb diet and I no longer take insulin and I have lost 40+lbs.
Not sure if T1s would agree but if this is what you are then you may need to change your lifestyle, as well as diet, to deal with the practical requirements of your condition.
As some form of T2, along with the diet I do as much exercise as possible (walking and gym) and I have brought my condition 'under control', quoting my doctor and a diabetic nurse. In this state I now have more flexibility in when and what I eat.
Hope this helps at the start of a new road in your journey.