I am very pleased for you and long may it continue but wish to sound a word of caution.
I also lost 5 stone in weight in just over a year after being put on Metformin and changing my exercise levels. Being on Metformin seemed to stop my body wanting more food and what I was eating was healthy anyway so the weight loss was easy.
The caution is where you seem to have been advised you don't need to do a check up as your levels are so good. This happened to me too as I actually ended up on 4.9 on the Metformin (16 on diagnosis) and was then taken off the tablets completely as this was far too low.
In my case this led to a long period where my body had been coping to slowly going back to where it was demanding more food again. The nurse however, sees me once a year and refers to me as a poster boy for what diabetics should do. Last meeting was a bit awkward as what I had been telling her for a while started to become obvious to her in the weight gain but she still wasn't convinced.
I have now made an appointment to see her again to get back on Metformin as I think I should never have stopped completely or at least should have been monitored closer for signs of it creeping up (although I was "only" 5.9 last test this is a 20% increase & I am sure it must be worse now).
What you have acheived is brilliant, just don't let this be an excuse for no one to see you to help maintain what you have acheived. Make sure you are strong with how you feel about things when talking to your medical team as it is likely they won't prioritise you for further help if you don't insist you need it.