It's always wise to ask your doctor for help. mostly, they try, but some are not actually very knowledgeable
as for your BG questions.
a non- diabetic BG is at around 5mmol/l at all times, mostly slightly under that. If it deviates, it goes back very quickly, generally within an hour or two. The numbers you give are FAR TOO HIGH and into the danger zone. That amount of glucose circulating through micro blood-vessels is doing damage, particularly to your retinas and kidneys.
If Metformin isn't enough to keep you in the safe zone, you have essentially 2 options:
1) change your medication
2) change your diet.
I personally find a reduced carbohydrate diet is better than taking loads of medication. It doesn't have nasty side effects.
If you feel this is the way forward for you, read the "stickies" which explain it and look at the success stories thread.
If you then have specific questions, Come back and we'll find someone who can answer them for you.
Hana