Mrewheeler
Funny thing is when I listen to the mix I still hear spots I could have fixed or done differently.
Everybody suffers from this syndrome, and it only gets worse as your critical-listening skills improve and you hear more and more things you can improve upon. It can lock you in an endless loop if you let it! You'll even start listening to commercial recordings and picking out things you would have done differently.
The trick is knowing when to let go of a mix, accepting that some flaws are necessary. I'm not there yet, but I've only been doing it for 40 years.