Hi,
I work on a diabetic ward.
First of all you need an appointment with a dietician so head back to your GP.
Secondly, keep a food diary, you should be able to work out within 2 weeks what it is that is pushing your blood sugars up.
You should test your BS in the morning, after that test your BS 2.5 hours after eating, that is when you will get an accurate reading.
It's trial and error to begin with, there are type 2 diabetics that end up on insulin at a later date, it could be that your metformin is not controlling your BS enough.
Also metformin is not for everyone anyway. It has side effects for some, weight loss is one of these side effects so keep a record of what you are losing on a weekly basis, the dietician will need this info.
The rule of thumb is that you should (within reason) be able to eat a normal diet but that depends on what is normal for you?
A lot of people try to enforce a healthy lifestyle when diagnosed, this is good but don't go overboard on fresh fruit and fruit juice as this will push your sugars up. Bananas are particularly high in sugar and diabetics should consume no more than 3 a week.
They say your sugars should be between 4-8, this will take a while to get to, it won't happen automatically.
I think you are being very hard on yourself, it will take time to adjust.
Complex carbohydrates are great for diabetics, and will help stabilise your blood sugars, like I say, make an appointment with your GP and get a dietician referal.
Good luck. x