Maybe have a few long layers cut in around the top of your head so that there is some lighter-weight hair mixed in with all the long hair? All that weight is pulling your hair down flat. My hair is 3a and waist length, too.
Search for the pixiecurl method of drying--this works best for me
Duckbill clips at the roots before and during drying?
Suave Professionals Captivating Curls Whipped Cream Mousse
Honestly, I have to flip my "bangs" and the hair at the top of my head to one side in order to create volume. Kind of a dated, wild lion's mane look. I'm okay with it, though. Not very polished or professional some might say. But, I don't care much about what some might say.