Take injectables once a week for atleast 6 weeks then take Cap Mecosule  OD ,( B 12 supplement) to be taken once a day , regularly.U can start with capsule from now onwards,and continue for atleast 2 mths. Secondly,as your HbA1c is raised,B12 usually gets lower with same ,it's called neuropathies. Secondly u being a vegetarian is another cause for low levels.But as u have been recently diagnosed with same and u being young will not be posed to these complications if u start medications/ insulin earlier.Do check your sugars ( fasting & Post prandial i.e. after 2 hrs of breakfast.this will give the estimate whether u need to start medications or only dietary modifications will help

Are u a strict vegetarian not even taking milk or eggs?..for now B12 deficiency is treated with injections for 3 months If it is nutritional B12 deficiency ,it will get treated by oral medication after 3 months But if not so ,u may have recurring symptoms even on cit B12 tablets...then u need to fmget further evaluated and treated accordingly Diabetes in starting stage causing this much B12 deficiency is little unlikely... For diabetes dietary changes with low carbohydrate,  low fat diet , physical activity are must,..BMI should be between 20 to 25

HbA1C seems to  show your sugars have been bad,, get a fresh Fasting Blood sugar and Post Prandial Blood Sugar and same day Random blood sugar around 4 pm, You might have to continue with B 12 injections for upto 8-12 weeks, then plan an oral medication for the same for next 3 months, yes diabetes and low B12 can come exist and besides your being vegetarian might need you to take supplements for a bit longer while, take protein rich foods

Pls share sugar reports. Take 4 injections and repeat B 12 tests.