It was probably your elevated blood sugar that was making you feel hungrier before. When you have glucose circulating in your bloodstream that can't get into your cells, your body thinks it's starving so you get those hunger pangs. The metformin probably is working for you.
It does sound like you've got a good endo., one who likes to get the answers and will educate you in the process... SO important!
Have you gotten a blood glucose meter? I would recommend one -- it's like having an extra pair of eyes to see what your blood sugars are doing throughout the day. It'll encourage you to see how the metformin is working for you, too. My mom was just diagnosed Type 2 in April so we went and just got her an inexpensive generic brand meter. She has been so good about checking her blood sugars before and then 2 hours after each meal/snack and logging what she has eaten. Because of that, she now knows what sends her blood sugars up and what doesn't. It helps her manage her glucose levels, and, so far, she has not had to go on medication.
I'm really glad for you that your GP was "on the ball" and referred you to a good specialist.

Keep posting!