Like several others have posted here you are in a great position to make some very simple changes that will have big results.
If you're looking for reading resources I found "Working Effectively with Legacy Code" by Michael Feathers to be very useful helping me build a plan. Yes it's an older book but that helped me appreciate this is not a new problem.
If you're looking for reading resources I found "Working Effectively with Legacy Code" by Michael Feathers to be very useful helping me build a plan. Yes it's an older book but that helped me appreciate this is not a new problem.