fusspot

informal To be very fussy or particular, usually to an excessive or unnecessary degree. So the trip will be a little bit different than we had planned—it's no big deal! Don't be such a fusspot. Of course Vanessa found some miniscule issue that no one else would have noticed. She can be a real fusspot sometimes. I'd be careful if I were you—if your report is too sloppy, Martha will make you redo it. She's a real fusspot, that one.

informal One who tends to be fussy or particular, usually to an excessive or unnecessary degree. Primarily heard in UK. Don't be such a fusspot, huh? This really isn't a big deal. Of course Vanessa found some miniscule issue that no one else would have noticed. She's such a fusspot. Now that I have to hand this report in to that fusspot Phil, I know it will never be good enough.