My hair is the same way! Back in 2008 I had a bob which was about chin length, (i was also straightening it nearly everyday...i regret it now), but I lost my curls and it was definitely in the 2's...probably a 2b. Now that it's about chest length, its definitely back at 3a. My only issue is I still have short layers (beginning about chin length) and they still aren't holding the curls...they're all wavy.
The hair on the bottom layer is all ringlets, it's just the top layer thats wavy. My hair is so thick though when I let the layers grow out its too much to manage. Sigh, can't ever win