Hi, if your a1c is 11.2 this means that your average blood sugars are over 300. This is terrible for your health and you are at risk for very serious complications along with stroke, heart attack, among others, in the very near future. Blindness, kidney failure, and wounds that won't heal are also high risk given your current levels.
With your blood sugars this high you need to be taking insulin. You should be taking fast acting insulin to cover meals and long acting insulin to keep your sugars stable and at optimal level in between.
You need to see a doctor and get properly monitored and prescribed medications.
Do you have a blood sugar meter? If you don't, please get one. your meter should be your best friend. You test after eating to see if the foods you ate raise your blood sugar. then you can adapt your diet.
Given your current situation and your extremely high blood sugars, if you want to reduce then using diet, then a very low carb diet / ketogenic diet would be the way to go. This diet however, may still not be enough to get your sugars down and you may still need insulin / other meds.
Please know that if you eat a ketogenic diet you need to follow it strictly.