Had a lumbar mri in sept 2021, a ct scan of my sinuses before surgery on dec 2021. now my doctor wants another ct scan of my sinuses after surgery due to migraines and pain behind the eye. plus dental and pcp chest x-rays. worried too much radiation?

Your concern is justified. However most places now do a 'low dose'[ CT so the radiation is minimized. Always ask your MD to explain why a test is necessary and what it will add to your care. Good luck

What's worse, the absolutely minimal risk of a problem from diagnostic tests, or the much higher risk of damage from asking your doctors to work blind, to guess.

I understand your concern, but modern imaging techniques use very low dose radiation, just enough to obtain an image on the super sensitive sensors of the machine. The exposures are of a diagnostic dose, not a hazardous exposure dose like from a nuclear power plant leak. Be rest assured that you will not develop cancer from what you've described.