Hi there.
I have never been over to this Forum because I don’t consider myself disabled, although I have had epilepsy for 24 years.
To me, epilepsy isn’t a disability – It’s a condition.
I have ridden and shown everywhere from California to Devon to Madison Square Garden to WEF.
Twice I have had seizures at shows (I only have grand mal); one time I was standing in the barn aisle, the other time I was standing on a mounting block, about to get on my horse.
It has never occurred to me to stop riding. Like the OP, I am well controlled and only have a seizure about every 6 - 8 years.
Perhaps I am not concerned because I have never had a seizure when I was really concentrating and my brain was engaged and thinking. Ergo (I rationalize) I will never have a seizure on a horse because I am “alive” when jumping and competing. My mind is focused and I already have enough neurons firing that there is no “room” for those aberrant and pesky ones to start a riot. 
Besides, what’s the worst that can happen? You fall off. I have fallen off hundreds of times (feels like it anyway) in the 50 years I have been riding. At least if I’m “out” when I go off, I won’t be awake to know that sinking feeling of “Oh Shit!”. 
I am only partly being blase (accent on the final e) about this. As I said, I have always refused to consider myself “different” from any one else because I have seizures. I refuse to let it define my life. I live life and do what I want to do; I will not stop doing anything that does not involve potential injury to others if I should have a seizure. – Actually I take that back – When allowed to by DMV, I drive. I know my limitations and I do not drive tired or distracted. When I drive I am constantly focusing on things around me, carrying on an internal dialogue with myself to keep myself alert; to prevent going into a “road coma”.
Because of that, I feel safer than 99% of the drivers on the road. I have never had an accident or gotten a ticket because I am hyper focused when I drive.
PS: Having no license is a bitch. Sorry about that. I have hired people who need extra income and/or are bored staying home to chauffeur me around. I have met some nice people that way.