It will be some time before I can get video. Definitely not before September. Meanwhile I must rely on proprioception, which I know is very unreliable. However I am fairly sure that only one goggle glass appears above the surface and only part of the mouth. Often on the right side I find that I am still breathing out as the mouth breaks the surface and I can feel and hear the bubbles. I think I get less air on the right side, probably because of this.
I suppose a possible approach would be to try to convert entirely to right side breathing for a while. I seem to remember that Howard Firby mentioned doing this with his swimmers in his book.
However, most top male pool swimmers are one-sided breathers, even if they can breathe both sides in a pinch. In open water I am more likely to swim breaststroke if I have to swim any distance. I have not entered the sea this year yet,and I had better hurry before it's too late. They tell me the water is quite pleasant at the moment.