You got thrown because you're out of position and out of balance.
First thing, both hands on the reins, hands low, in front of the saddle horn so as to shorten up the reins, not high and close to the chest. In such a situation, pull the reins back toward you, not up and back so as to keep the head down.....
Heals down..very necessary if you don't want to go over the front.....position yourself in such a way as to have balance...sit slightly back in the saddle.
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.