I agree with Brenda and Equestrian Life, I would add that you can try standing in your 2 points position with shortened stirrups to lower your leg. Another good exercise is to do raising trot without stirrups.
You could also try doing squats and other leg exercises with a medicine ball or other weight held between your knees/calves to help develop inner leg muscles.
Squats, calf raises, balancing on a stair/step with balls of your feet (like a stirrup). Hope this helps!
Work without stirrups for sure! Two point also helps not only your leg but balance! Bareback could be an option as well!