I think you just need to find clothes that are comfortable and allow you plenty freedom of movement. Plus, it's nice if your clothes give you confidence, too!
If you need some cheap leggings and a tank top,I'd recommend https://www.fashionsonder.com
I am petite as well. I agree that fitted pieces are best, especially tops. How many times have I had a floppy piece fall over my mouth or even my head - it gets warm in there!