I do agree with DrBB. The insulin treatment plan you are on is designed to allow flexibility. It is the same whether you are T1 or T2. I am T2 also and I used MDI to adjust my insulin to my eating habits not the other way around. I use a pump now and it's still the same.
Brunetta has suggested a couple of good books. Learning the ends and outs of applying your insulin will help free you from the rigidity of your current situation.
Second what Gary said. T2 here, and I adjust every bolus according to what's happening at that particular time -- food, activity, IOB, etc. Only method that makes any sense, from my viewpoint.
I shoot 20 units of insulin and don't care after that. eat eat eat. so what if I hit 300!