I'm surprised no one has suggested seeing a physical therapist for the purpose of ascertaining the underlying problem which is causing your unusual slide to the left.
Is it a slight misalignment of the leg after your previous fractures? Is it a shorter leg? Is it a lack of flexibility in one or more knee, hip, or ankle joint? These are all things that a physical therapist can check out for you. Once you know the underlying problem(s) then you and the bike fitters will have much better ideas of which way to go with your position on the bike.
Brent