Hi Blackcat
There are three scenarios as to why you can't get lower levels
1. You are eating too many carbs
2. Your pancreas is worn out
3. You are not a Type 2 and are really a LADA/1.5
You shouldn't have to suffer with the meds. I used to have terrible tummy problems with metformin until I gave up wheat. If you do this and still get tummy troubles then go back to your GP and ask for a referral to an endocrinologist who may prescribe Victoza/Byetta which are injectables.
I find that this website
http://www.dietdoctor.com/lchf gives a good idea about what to eat and how to cut carbs. My rules are to drastically cut the amount of bread, pasta, rice, potatoes and anything made of flour, so a good rule is to cut any white food out of your diet (or could be white if it wasn't wholemeal), the exception to this is dairy and cauliflower. Vegetables that grow above ground are good, test for other vegetables. Fruit in moderation, any fruit ending in berry is best, other fruits if unripe can be eaten.
I'm on 3 x 850mg metformin and 40mg gliclazide and if I don't follow my rules can get fasting levels in the 7.0 instead of 5.5 where I like to be.