I can relate to that. Unfortunately while it makes your seat FEEL more secure, you can be at higher risk of falling / hurting yourself if you ride with too-short stirrups, and with slightly longer stirrups you'll have an easier time getting your leg on and keeping it on.
In the picture you just posted your leg has swung back quite a lot, you need to keep your calves on and avoid pinching with your knee. In general your center of gravity is too far forward over the pommel of your saddle, bring your lower body back to remain over the center of your saddle and bring your shoulders back. EYES UP! Your release actually looks pretty good there, are you starting now to work with more contact over jumps? With the same release, but still holding contact with your horse? It LOOKS like it in your most recent picture but again I'm not sure.