28 is still quite youthful. I'm pushing 38 and feel better now than I did at 28.
I've seen a good amount of ballet in my day and many of those dancers are ripped - it's a great look and good goal. However, there is divide between eating clean and being deficient in calories. Dance and body weight movements burn massive calories and you need to take in more than you burn off to make gains (i.e. bulk up a bit). As a vegan you need to work a bit more to get the calories you need to be an athlete. Fruits, brown rice, nuts, avocados, and cereal grains (and yes, suppliment protein). One can not make gains on greens alone. Eat more, drink water all day, and get solid, consistent sleep.
Also, even though you're not the "gym" type, there are likely things you could do that would help with your dance and your wall flip goal. Take a look at the olympic lifts - the clean and jerk and the snatch. These two lifts create explosive power in your legs and do good for your upper bits as well. A lot of these lifters bust out back flips like no big deal and have a vertical leap to be envied by NFL running backs and NBA players. And if you examine the men and women in the lower weight classes they are built like gymnasts - not refridgerators. These two lifts would likely translate to improved dance in better leaping ability, throws, and catches (sorry if my terms are incorrect, I'm a lifter and not a dancer).
Good luck and here's hoping you flip out soon!