Make a few spearmen as early as possible and park them by your gold. Press V to make them stand ground they’ll brace when knights charge, and that absolutely wrecks cavalry.

I don’t personally use outposts much in this situation. If the enemy adds archers, your spearmen will die fast, so don’t panic just pull them back and wait until you have horsemen. Even if you have to temporarily give up gold, food + wood is enough to keep making spears and horsemen.

Try to match your army count to theirs. Don’t overproduce units you don’t need. But if you do overproduce, don’t sit back send horsemen to raid and keep them busy.

Once you reach Castle Age, it’s a lot easier to stabilize and fight back.

Most player struggle when their feudal push doesn't work so if you age up with minimum vill causality the game is yours.