Trying Bilateral Breathing

In recent years I have greatly improved my breathing technique, and last season became very comfortable swimming 1500 - 2000 meters at a time, breathing to the same side (left and right on alternate lengths) with no sense of being out of breath. But I felt in a bit of a stroke length and speed rut. I have always found bilateral breathing a lot faster than breathing to one side, but I usually feel desperately out of breath after about two or three hundred meters. So my experiment for this season has been to incorporate bilateral breathing into my long practice swims. To retrain my body, I quit same-side breathing altogether. I started by alternating 50m crawl lengths with 50m easy breathing backstroke lengths. On the first few swims, I was desperate for air before and after the flip turns, and gasped as I surfaced in backstroke. But a few swims later, I was not feeling so bad after the turn, and stroked hard on the backstroke. By about 600m, bilateral breathing was feeling like the right and proper way to swim. Moving to the outside 25m lanes last Sunday, I swam three lengths of crawl for every one of backstroke. Due to a sprained ankle I was doing open turns, which gave me an extra breath, of course, and I felt no air desperation at all. I knew that flip turns would be more challenging. Tuesday I swam a full 1500m of crawl and 500m of backstroke. I was able to manage flip turns with tentative pushoffs. I found that extra breathing just before the turn tended to mess up my flip timing, and I had to tuck a lot to make the rotation. For about the first half of the swim I stuck with bilateral breathing, but gave myself extra breaths before and after the turns. I even tried breathing on successive strokes, like Sun Yang, but I don't exhale fast enough to be ready for the next inhale. For a few lengths I tried breathing twice to the right and once to the left, and eventually settled into breathing twice to the right and twice to the left—which seemed to be enough air. About three quarters of the way through I remembered to spread my fingers, though I forgot again in backstroke.