Ah, OK, then you meant you are on the correct lead (canter), not the correct diagonal (only used for posting trot). Makes sense now.
I still think doing more general riding and flatwork in two-point would help build those muscles. One of my instructors is known for rushing people along faster than they want to go, but even she makes people spend months doing flatwork in two-point before she lets them do even low jumps.
"Saddle fit -- it's a no brainer!"" - random person