What to wear, what to wear?

I'm encountering a really important ballet issue. What does a "vintage" woman wear to class? Because the classes I attend are for adults, there is no need for pink tights, black leotard, hair pulled back combo that the kids have to abide by. That said, I'm not comfortable wearing my gym-rat clothes. 

I've been searching online for appropriate clothing for class. My fellow students mostly wear gym clothes, typically leggings and a loose top. A couple wear leotards and loose pants, banded at the ankle. 

Last Saturday, I committed a ballet class faux pas. I wore black leggings and a loose top with a fitted cami underneath. After the first class, I became very warm so I shed the overtop. This was so not Audrey Hepburn (my fashion idol), so "Shame on me!" I won't be doing that again, despite the fact that the classes are held in a community center building, not the American Ballet Theatre studio. 

I'm starting to learn the 'secret rules and regulations' of ballet. Very important to know! Such as, you turn toward the barre, not away from it, when switching sides. Who knew? Or should I state, "I didn't know that." Now I do, so that's progress. 

Any suggestions about ballet attire for the mature set would be really appreciated. 

Dancing onward.