Too much metformin?

So I am on my 8th day on Metformin, and along with drastic diet changes and now incorporating exercise my BGL are getting better and better:

[big dots are my fasting BGL / Line to show progress path]

Right now I am taking 250mg in the day and 250mg at night. My Dr. right now has a plan to up my Metformin dosage up to 500mg in the day and 750 at night. I am starting to wonder if those levels will be too high for me or if as my Metformin dosage increase if I should include some grains and starches in my diet.

Thoughts?