Originally Posted by
onbike 1939
Before doing any more work on it I'd check that the hanger hasn't been bent.
Agree. This is the first place to look. Your LBS with a complete shop and good mechanics have the proper tool to check this. You can't eyeball check the rear hanger unless it is way out of alignment. Also make sure the limit screws are set properly.
In one photo it looked like your limit screw on the smallest cog is slightly out but, that may be an illusion. Try using the barrel adjustor to fine trim the settings.
I built up a friends compact centaur group on a bike I borrowed for the Ride Virginia and I found it took more than the normal care to get right. Your chain is on the shorter side but should work as is. You are at the limit with the short cage RD. Your cogset looks like a 13-26t if you go to a 13-29 you will need a medium cage at least.