I'm Greek, which also enjoys a good cav bonus. It only gets more and more difficult to win with a cav only strategy. As you grow, the players around you get better at defending their bases, for the most part. You will have to develop your attack strategies away from Knight spam. Knights take a hefty penalty when attacking non-defense buildings and defending troops tend to distract knights from doing what they do best..taking down defensive buildings. Ever see one of your knights get attacked by a defending troop and watch them do a one-on-one fight while the rest of your knights take off?
Right now, I use 12 knights, 14 guns (archers) and 9 spears.My guns take down defending foot soldiers and my spears take down defending cavalry while my knights do what they do best..take down defensive buildings.
Drop cav first. Take down a catapult. Your cav can take a lot of punishment. Taking down the catapult is to help your other foot soldiers so your cav aren't unsupported. Either drop your spears and bows behind your cav, which was just cleared, or drop them on spawning defending troops so your cav are free to work. Just don't drop them in such a way that they are closer to catapults than your cav are. Catapults will attack the closest target.
I myself am possibly in the middle of an attack strategies change. I have bombards available soon and I have supply wagons. I can't play wagons, cav AND bombards. I'll be experimenting with cav+wagons and spears and guns to support. The supply wagon gets a hefty heal bonus when it heals cav that it doesn't get with any other unit. Between that and the tactics heal and protect which work especially well for high life units, I am hoping this will be a workable strat and enable me to continue to take advantage of the Greeks unique unit. I may have to give up on the cav approach and use bombards and foot soldiers, though. It's already a proven strategy. We will see.
This game will make you grow and develop new ways of playing. Be open to revolutionizing your present methods.