Very first.......Swing at strikes. Swinging at bad pitches screws you up. Not just bad results, but changes your mechanics.
Second.......... I would start earlier and more leisurely on my bottom half. Get your front foot up early and stride into the ball, timing your foot hitting just a split second before contact. If you start late you have to rush your mechanics, but if you start earlier, you can be slower and more relaxed on your lower half. You want to think..........
Bottom half, ease into the ball
Top half, explosion
Give this a try and see how you feel.