Agreeing with the previous posters. Maybe you shouldn't punch the disc backwards to reach back so that you don't start the pull with the plyometric loading released from the reach back. From your back and side plus maybe a bit from the shoulder unloading during the pull. That free power can fool into adding to the acceleration straight after the unloading ends. It's a feel and unconscious thing for me at least. When you try to keep the rate of acceleration similar you hit top speed way too early. Try to be mellow and let the unloading of muscles and legs and hips do the work initially and stay relaxed with your arm until the arm and pivoting brings the rear of the disc to the right of your right pec and then pull quickly. Until that let the arm laze about and be on holiday on the beach tanning sipping a cool drink. You need to find a mental image that allows you to wait with the power usage of the arm until unnaturally late feeling powering for many instinctively. It's your instincts that you're fighting against and you need to convince yourself of the benefits of lazying about until the god part of the throw late in the arm pull.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.