Improvement strategy for older adults

What you really need is opening theory.
Chess is mostly a well-established discipline. You have to know the lines so as to be able to navigate towards a favorable endgame. This gap in your knowledge is what makes it feel like you are 'just reacting.'

You also need to choose some tactical points to move towards with the whole of your pieces. For example, f7, b7, h7, h6, e5, g6, or d5 are common 'hot points' for white, and the mirror-image of those for black. You have to then practice maneuvers to get an infiltration going, for example establishing an outpost knight on e5, c5, f5, or c6.

But the best thing is to choose 3 opening systems: one for white and one for black vs. e4 and one vs. d4. And then you study the theory. Moves get very specific, for example an f6 knight that's being kicked often stands best on e7 vs. e4 or g4. It's this body of knowledge you need to build up for all pieces in all opening systems and all phases of the game, and then adding tactical patterns. Always use an engine to evaluate every game, too. Then you can develop your own game in a later stage. Yes, chess is huge, I know, but the acceptance of that fact and conformity to the chess establishment is the only real way to proceed, otherwise people are just murking on.