I am an on and off member here and thought I should add my two cents worth to this discussion.
I have been diagnosed with T2 in 2013 and have tried almost everything since then to achieve a good balance between sugar numbers and quality of life. My current approach is to completely cut out meat products and heavily restrict dairy consumption (Just the coffee with some cream and some dessert once a week) I have noticed that since taking this approach, my diabetic medications have been having a more pronounced effect to the point that I have reduced my Insulin dosage to a bare minimum and still see fasting numbers under 8. (These used to be 11+ at one point despite more meds)
After everything, I would say that it all boils down to just one word, "discipline". There are a few things that you have to be a bit of a fanatic about but they can be really worth it. My personal tips would be:
1) Restrict yourself to two hearty meals a day with maybe a tea/coffee somewhere in between.
2) No meat substitutes. No matter how fancy they sound. Vegetable products stuffed with chemicals to make them look/smell/taste like meat are an absolute no no.
3) White breads/pasta/rice should be replaced by brown counterparts while restricting their portions to under 80g of carb per meal. This adds up to 160g per day.
4) No processed sauces etc. The less food you consume out of plastic/glass packaging, the better.
5) Hydrate regularly
6) If possible, fast occassionally. Fasting has traditionally been part of all cultures and for goood reason. I have noticed that doing IF for just a week can improve fasting numbers.
7) Some moderate exercise to top it off. Walking vigourously for even 30 mins can have a wonderful effect.
To answer the OP's question, plant based diets can be helpful but it is also very easy to get them wrong.
You are doing a number of things that will help to bring down your blood sugar figures
1. intermittent fasting will be great
2. avoiding processed foods will always be better.. fresh cooked single ingredient products always.
3. many of us have found that brown carbs are just as bad as white for blood glucose rises so this may be why you are still seeing 8's
4. again processed foods are definitely bad so yes.
5. drink when thirsty agreed
6. fasting along with carb reduction ( or total elimination) is one of the strongest therapies I have found.
7. walking yes but I don't do more than that.. having a dog helps.
I seriously doubt that avoiding meat and dairy has had any significant benefit for you in reducing your blood sugars though it has been the other things you have tried.
If you cut out brown carbs and re-introduced meats I'd guess your glucose numbers would drop further.