Any idea what's going on?

Hi, I was diagnosed with type 2 in 2015 hba1c 143. Initially diet controlled, (low carb)started taking Metformin in 2020 because hba1c never went below 61. I never lost weight even though I ate a low carb diet. GP agreed to test C peptide level which was 1900 at the time.
In October 2024 GP prescribed Rybelsus and advised me to eat some carbohydrates. I started to have 2 slices of toast with butter every morning for breakfast. Stayed low carb for lunch and dinner. Gained 8lbs and hba1c went from 51 to 63 in about 6 months to mid Jan. GP repeated C peptide test result is 1852pmol/L and agreed that I could stop taking Rybelsus.
I have cut out the toast and have been low carb since mid Jan. Started testing on Monday and fasting level has been high since then (around 20mmol/L.) This morning my fasting level was 17.0 so I tried oat bran porridge made from 30g oat bran and whole milk. 2 hrs later 24.9mmol/L.
I'm having a review with the practice nurse on 9th March and I don't know what to ask her.
I'm sorry for the long post but I have tried so hard for years and nothing seems to change.
I really don't know what to