Welcome to the club nobody wants to join. Metformin is offered to most diabetics since although it does precious little to reduce blood sugar levels, it has a protective effect on the heart and blood plumbing in general. Max dose of Metformin might reduce your bgl by a couple of mmol/l at most. It is a difficult med for many since it has gastric distress as a common side effect. But the effects generally wear off after a while, and I was on max dose for over 20 years.
I found that a low carb diet was more effective than any diabetic med (apart from insulin, which I do not use) and it brings my bgl into control and the last 7 years I have had below diabetic HbA1c blood tests.
Use the Libre to see how you respond to different meals so you can identify those that will help, and those that hinder bgl control. keep a food log and record readings as you go. We normally work by taking a reading just before eating, and then 2 hours after eating, and the difference should be 2 mmol/l or less if the meal is beneficial. above 2 then it contains either something too sugary, or was just too much in portion size.
Think diabtetes = Carb Intolerance. Carbs make us diabetics sick.