Only best advice I can give is to put a little superglue on you fret fingers to reduce pain and rough up the grippy part of the pick (gentle pressure making notches with a nail cutter, hammer on concrete or some such). You can also use a paperclip as a plectrum to change the angle on your strumming hand so you can change angle on the fingering hand. Right thumbnail in the slot against your right index. It lets you stroke with your picking arm at 90° to the strings.

I learned to play with it laying on my lap so my fingering was wonk from the start but mostly it was motor nerve therapy and training - I get cramps very easily.

There is a tactic of getting a 12 string and stripping the second strings off which will give you a little more room between your fingerings.

Have you tried thumb-out fingering? Have you watched Alexandra Whittingham's more vertical classical position?