I had a similar journey.
Metformin didn't do much, blood sugar was slowly increasing by the day...It got to the point where I had constant ketones in my pee, at that point my doctor stuck me on Insulin. Usually Metformin will see to resistance issues.
If you are eating carbs and you're still producing ketones it means your body is unable to shuttle the nutrients into your muscles due to a lack of Insulin, that is why you're on Insulin.
It's not so bad, you don't have to have a super restricted diet like most T2 diabetics. I eat whatever I want and just inject the appropriate amount of Insulin, it works for me as I make sure I exercise regularly. If I try to do the same without exercise I put on fat, which makes perfect sense...
Just learn how to use your Insulin, work out a ratio of Insulin to carbs (I include protein into my ratio as I consume a lot of protein and find it affects my blood sugar levels). You'll probably that not all foods have the same effect, for example I need a fair bit more Insulin with rolled oats than I need with straight sugar - why? I'm not sure, but my rolled oats ratio is different to my simple sugar ratio.
I'm managing to maintain blood sugars of 5-6mmol through out the whole day while eating around 200g of carbs (mix of slow/fast digesting), around 150-250g of protein and probably around 60-70g of healthy fats.