After pancreatitis, quite a few people develop T3c: basically the pancreas gets so damaged/scarred, the insulin-output just isn't what it should be, or stops all together. Ironically enough, a lot of GP's have never heard of T3c, so you're better off with a specialist. Particularly since, if this is what's going on, you will indeed need insulin; a diet and meds that increase sensitivity or force output where where is none to force, aren't going to make a dent, if you don't produce enough of your own insulin anymore.
We can't diagnose on here, and a lot of what I'm saying is pure speculation, but a specialist diabetes nurse, well, sometimes they know a thing or two, and sometimes they don't. You could ask for a referral to an endo, which might be better far as diagnosis goes, because it sounds like someone's just playing a guessing game now, and not actually knowing what tests to order for you.
And if at any time your numbers literally do go sky high and you feel ill, just call 111 and ask them for advice. Add in that there is uncertainty about your type at this point in time, but you likely are T1,5 or T3c which is all still being investigated, and you're currently ill. They'll let you know what to do next.
I do hope you'll feel better soon and get some answers!
Jo