What are your insights for prioritizing caste age over army?

I have played this game for years, once every Sunday with my dad against HD hardest AI. I don't strictly follow "build orders" but from experience I can do decent up times. I have played mostly team games and recently got serious about the ranked 1v1 ladder. I was placed at 900 DE elo and quickly learnt that I need early walls to win, I learned that TCs are crucial to prevent raiding and now I place them in better positions. I also learned that denying resources is extremely important to disrupt build orders.

Right now I am sitting at 1098 elo, I got here after 21 games using only scout and MAA rushes. After getting paired with 1100+ guys I realized that I need to do damage earlier. I tried to do something that looks like drush+FC, it worked (one or two vill kils plus idle time) but at my level a drush means a lot of inefficiencies and idle time in my base, thus, the long term difference with my opponent becomes very small. Overcommitting to feudal aggression (after a drush) seems to be a much more effective option. I just keep military production and even if they beat me to castle age I loose less frequently.

I have two questions, one is: Apart from knowing the build order (which I roughly do), what else do I need in my mind to do a decent drush+FC?

Second: If I go for feudal aggression, what are some signals that I should stop (or reduce) military production and prioritize going to castle age?

Keep in mind that my mechanical skill is far from amazing and it will stay there for a while.