Hi, I don't want to give you advice because I'm certainly not qualified but I can tell you a bit about what I do and my version of things.
I think you should keep taking the metformin. Why? Because normally with it you are not at risk of getting a hypo or put otherwise get "to low".
We all want to see a small change in our lifestyle result in a instant and definite change. We don't work like that.
Fasting "might" get you a lower fasting BS level but it will not be on the very first day. If it will happen at all.
16:8 might sound and feel like a big deal, but if I'm correct you are just skipping breakfast. That sounds as if I'm saying "Is that all?" Which is not what I mean at all believe me! I started with skipping breakfast, then changed my lunch to a Atkins bar, then skipped it all together. And I remember how hard it was in the beginning. Now I get nausea thinking of breakfast
Personally have been on one meal a day for a little over a year now, taking my meds as if I where not, and due to dawn phenomenon my fasting BS is still ... emm not that good most of the time. But it generally is a lot better the rest of the day.
Hopefully you have a good diabetic nurse, but if you read more of the forum you will see that a lot of peoples experiences are not optimal to say the least. You can read/watch about what works for other people but in the end it's all about what works for you. Maybe a form of fasting, more likely or directly a form of low carb high fat diet if you are willing to try.
I take it you check your BS yourself? What kind of values are you seeing throughout the day? And what are you eating when you do eat? Even when you fast, if the one, or two, meals you do eat are somewhat carby you (I) will see that reflected in my fasting BS the next morning.
Also I agree with Fenn, might be easier, and better, to just change your habit then to do it a couple of days a week.
It' more then a bit soon to tell but look up dawn phenomenon. For type 2 it's rather common it appears and different things help for different people.