Welcome to the forum
It is a shock to receive a diabetes diagnosis and yes your HbA1C is high at 107mmol/mol ( normal is below 42 and diabetic anything over 48) so certainly at a level to need to do something about.
Some people do get stomach issues with the metformin and so the dose is usually started slowly then increased gradually but there is a slow release version which causes less problems.
The main thing is to address your diet in reducing carbohydrates but your nurse was being rather extreme in saying cut out all carbs as that is very hard to do. But reducing them to what is suggested for a low carb approach is less than 130g per day. You will need to start looking at food packets for the TOTAL carbs or google a food item and make your choices wisely.
Avoiding the high carb foods like potatoes, bread, rice, pasta, breakfast cereals, tropical fruits, pastry, as well as the obvious cakes, biscuits and sugary drinks including fruit juice or at least having much reduced portions.
There is plenty you can eat as meat, fish, eggs, cheese, full fat dairy are all zero or low carb and good choices of veg and salads and fruit like berries still gives you plenty that you can eat.
This link may help you with ideas for meals, it is a low carb approach.
https://lowcarbfreshwell.co.uk/
I'm not sure about the remark about finding out in 6 months whether you are Type 1 as unless you have had the blood tests for that, those being c-peptide and GAD antibodies you are still not necessarily going to know, high HbA1C is a pointer but sudden weight loss would be the other thing.