Agree that there should be more "testing of diabetics to establish actual insulin production", to avoid misclassification of T1s as T2s. And not only when people initially become diabetic, but also if their 'clinical presentation' changes.
As I've said in another post: it seems the problem is that C-peptide tests used to be very expensive and difficult, they aren't anymore, but a lot of medics don't seem to have realised this yet.
But-- if, for you, "it needs close to keto to keep ... the weight off"-- that proves definitively that your body is producing enough insulin. If your body was not producing enough insulin, i.e. if you were T1, your weight would drop like a stone (if you'll pardon the pun), no matter what you ate, and in particular no matter how many carbs you ate.
The likeliest explanation is that, even if you're now relatively slim overall, you still have enough visceral fat that you're still T2. In principle, there is an easy and definitive way to find out-- by doing an MRI scan of your abdomen. Unfortunately, MRI scans are still very expensive!
Alternatively, you could actually try a VLCD-- the Newcastle Diet or the NHS programme-- as these have been proven to give you the best chance of losing visceral fat.