Welcome kdiebelius
Not sure where you live - if in England and Wales, then NICE guidelines apply; if in Scotland, SIGN guidelines are used.
Any decision about the right course of action to treat your tonsillitis will take acount of your age (at 15 years, you are considered a child), and the potential benefits - potential to improve issues such as how much school you are missing, effects of tonsillitis on diabetes control etc, balanced with the fact that surgery, particularly healing (tonsils are very prone to bleed and / or get infected, even more so with high blood glucose levels) is more of a risk than in someone without diabetes.
In the meantime, even if you can't eat, you can still drink and get enough carbohydrates and other nutrients in things like soup, yogurt, ice cream, soft drinks, warm drinks etc. If you need any advice about diet during tonsillitis episodes, then ask to be refered to a dietician, preferably one with experience / special interest in diabetes and teenagers.