Hiya!
Do you know why your new nurse believes you are Type 2? They frequently get it wrong.
Do you know what tests they are doing? I suspect they are doing a GAD antibody test (among other things). If the find the antibodies present in your blood, they will know you have an autoimmune type of diabetes (Type 1 or some similar variant) - if they don't find the antibodies, they will probably plump for Type 2 (although not all Type 1s have the antibodies, so it's not conclusive).
As Sugar2 says, some of us have a condition called LADA. This is an autoimmune condition where the antibodies attack the pancreas beta cells and eventually kill them all off. While the beta cells are still working, we produce some insulin (and are therefore not Type 1 as they produce no insulin). However, we might not produce enough insulin and the production of insulin diminishes over time. Those with LADA usually need insulin within 4 years of diagnosis. Although it's a variant of Type 1 diabetes, LADA can exhibit some traits of Type 2 diabetes. In particular, some LADA people are insulin resistant like many Type 2s - which could explain why you're on metformin as well as insulin. However, I don't know enough about metformin to comment on that.
However it turns out, at least you'll know what type you have and can then start making sure you get the appropriate treatment - so that's a good first step. Let us know when you have your results and what treatment you are offered, as people on this forum will probably be able to give you appropriate advice then. As for negligence, so many of us seem to have been misdiagnosed that I think there is just widespread ignorance of diabetes among the medical profession - even among some consultants.
Good luck and let us know how you get on.
Smidge