Just I think I post my story about breathing to give motivation and tips to people who are still struggling...
I restarted freestyle swimming about 5 months ago. The same as with others, I do several sports, I am fit, but I was out of breath after 1 length of 33m pool. The relearn process included technical refinements, TI instead of survival freestyle, I lengthened my stroke from 36 to an average of 27-28, changed to 2BK, etc. But the breathing did not came. I managed to do 2 lengths, but there was no chance for more.
I used bilateral breathing, as it is symmetrical, and from earlier experience it came naturally. Then I tried breathing at every second stroke, but it felt awkward, asymmetrical, but I realised that it was closer to normal breathing. Exhalation into the water was not the best at the beginning, but I improved and managed to exhale into the water normally.
Then read about the bobs, I practiced, and made some progress, or at least I was able to swim 2 lengths in a row whenever I wanted. But no progression towards 3 or more...
Then I realized, that the most important factor is to breath naturally. Or at least as close to the natural way as possible. That also means that in case my body tells me to breathe, I should breathe immediately, or tension and out of breath feeling increases, and I needed to stop. This brought me back to breathing at every 2nd stroke. And voila, it works. First 4 lengths in a row. Next time 6. Next time 18 (600m), today 26 (nearly 1 km, and I stopped because I reached the daily target 2 km). Every day it gets easier. For symmetry I keep alternating the breathing side at every length.
To sum up, find your pattern, what feels natural, and stick with it!