You're doing the right thing. Trying to struggle on makes things worse (but sometimes we need someone else to tell us what we already know deep down). Remember that with raised sugar and possibly ketones, you effectively have a bad hangover on top of the viral symptoms that non-diabetics get (but without having enjoyed the alcohol). Non-Ds will be more insulin resistant when ill, but their bodies will deal with it automatically - no need for mental arithmetic, the blunt instrument of manual insulin doses or a crystal ball.
Hope you feel better soon.