Well done on what you've achieved already! I would guess that your improvement in blood sugar is much more to do with your change of diet and your weight loss. Metformin actually only makes a relatively small difference to your blood sugar readings.
You've obviously got a meter and are testing. Carry on your good work, and test to see what foods affect you and what you can eat safely. I was diagnosed just under a year ago and had fasting blood sugar level of 18. I decided to try and control with diet only, refused medication - why take something if its not necessary? Only you can decide whats right for you. Once diagnosed, I think we are never cured - but can be under control at normal levels.
Good luck.
Anne