When you say your readings are 7+, do you mean in the 7s or are they going considerably higher, in the teens for example. In the 7s is not particularly high. Also, perhaps you are having some side effects of metformin? I don't take it myself but it may be something to discuss with your doctor.
If you have cut down your carb intake, that will make you feel like you suddenly run out of steam. You normally need carbs to maintain energy levels but, watching your carbs is something you need to do as a diabetic. When I cut down on my carbs in the first few months, I had to go take a nap. Now that I eat carbs which release more slowly and now tha I am more used to the new regime, I don't.