Years and years ago, when I looked almost human, I joined a creative dance class (just ladies) and actually wore a very nice lilac-and-silver striped Lycra leotard over some thick pale blue tights, and had woolly legwarmers over my knees, plus quite attractive pastel-coloured trainers. The leotard was skin-tight and seemed to do the job of a sports bra. I also used to do Scottish dancing, but by then my bust had increased and it was a bit of a wobbly job, bobbing about in an eightsome reel. I nearly hit myself in the eye several times.
I'm only 34" bust, but with size F cup, and this is the problem. You can get larger band sizes, but size 34" bras usually stop at a D cup.
Front-fastening would be such a help. My husband is always kind and helps me, but it's a bit undignified. He says it's like saddling a horse, the cheeky thing.