Hello,

Yes you are right stretch and strengthing will help but treatment such as hands on therapy will help to improve faster.

Anatomy trains and myofascial release are really good however is complementary to the whole treatment approach!

Stretching will help however you need to stretch some muscles prior activity. In ur case ur Left side requires the most stretching while the Right requires more strength. Therefore You may want to consider prior exercising to stretch only the Left side and strengthen only the right side. At the end of the session stretch again only the Left side till things are balanced. Find a specialist that can further assess the tight areas and to provide you with protocols or even to get hands on modalities.

The Pelvis sounds again subject to selective muscle tightness and elongantion. same with above more or less you need to isolate those and indentify what is doing what with the help of a professional. Nevertheless if you fix the scapulas the pelvic distortion you have observe may disappear aswell

Have you done any athropometric xrays are your bones symmetrical (Am reffering to big differences and not milimeters)

And Yes it was your sport that has cause that imbalance makes perfect sence considering the sports muscular and postural demmands.

Are you demostrating the exercises to your clients with one side only? That can also contribute to your imbalances

Lastly i see you Patellas are quite externaly rotated you may want to also have a look at that as well