If the metformin and diet don’t make a significant difference in the next few days then you may need to decide if you are willing to start insulin or try some of the other type 2 drugs. How much metformin did your Dr. prescribe? How low carb are you eating and how low are you willing to go?
Walking is great for reducing BG’s and walking after every meal will help even more. The more fit you get the more likely you will get a handle on your BG’s without other drugs but if you need other medications then that’s just what you need and insulin is not as scary as you may think. You just need to be careful of lows and check your BG more frequently when on it. You will probably get a lot more tips and responses if you start your own thread BTW.