A couple of simple points. You state that you wear yourself out, how much of this tiredness is a result of mental exhaustion vs physical? When we want something so bad and are trying so hard the results will never be what we think they should be. I have followed your journey and can only say SLOW DOWN ENJOY THE MOMENT AND SWIM TO IMPROVE, not be the fastest or what you want to be a year or two years from now. I have been doing TI for two plus years and the most rewarding piece of the whole puzzle is having gained a sense of challenge and yet satisfaction with the improvement.
Today for some reason I felt like my 2 beat kick was actually initiating the hip drive. Ironically the motion and sensation was exactly what Coach Brian stated above. This did not happen overnight and I will try to reproduce tomorrow. It is a process don't let hurried expectations get in the path of incremental improvement.
Madvet made a very good point about drilling. They are learning sessions.