Is it down to my Metformin? (500g twice daily)
Probably not, most people may experience the opposite effect.
Less than 1800 cals daily.
Some people might get away without worrying about calories but not everyone. It's as good a way as any to measure what you're eating and if you're already seeing that your outcome isn't matching your actions, it's worth making a note of calorie intake, it's what medics use as a measure of food intake.
I benefited from cutting carbs down to about 40gms per day but then that also cut out about 700 calories which I didn't replace with eating more fat. My body doesn't tolerate too much fat anyway. Like everything to do with diabetes, one size does not fit all and you may have to spend time "juggling" with different ideas and to make our lives interesting we're juggling ways to keep BG down and ways to lose weight.
One thing I would suggest is that you keep an accurate food diary. There's nothing worse than some medic telling you that you probably "snack" too much or are eating more than you think. Keep a diary and show it to them. I weigh everything as well, so there is no question mark left over my food consumption.
You might like to look at your medication as this can thwart our efforts to lose weight. Steroids are notorious for causing weight issues and things like Gliclazide don't help (I gained 10 kgs without trying).
All the best at your review, just go prepared with the information.
BTW, I understand the "peeved" bit. I used the Harris Benedict formula to calculate how much I should eat, I tried 500 cals per day less, 1,000 cals per day less, I did loads of exercise, swimming, resistance stuff, golf, net result nothing. Low carb and lost 4 st then nothing, I go on holiday and always lose weight (there's the answer, permanent holiday somewhere hot). Just trying Newcastle Regime, too soon to say.