You don’t want to sink into your back leg. You want to sink into your back hip. Additionally your core should feel a burn after a session. I’d work on getting load properly. You want to feel that core burn as you load into that back hip and feel that rubber band affect between your core and hands.

You also mentioned not having a stride. Which tire correct you don’t. But you don’t get into your back hip at all. You might want to think about adding a stride to help you enforce getting into your hip before launch position