Not sure this is an 'answer' but I think it's possible you don't have one (bow wave) on the weak side. When I started bilateral breathing I found that not only did I take on water, I felt like I was sinking AND I was slowing down, nay grinding to a halt on that side.
I think that over the course of a few months as I got better, less of my weak-side pull was wasted on lifting me up and I began to get a little propulsion. Maybe focus on what your right arm is doing. ? Good luck!