Free Document Cloud Quota Error

I have a free Document Cloud account. It has a 2 GB capacity, which is fine for my uses. I believe I am well within that 2 GB storage capacity, though I don't know how to check on what my document storage volume may be. I get a Quota Exceeded error lately whenever I try and upload a new document to my account. My questions:

1. How do I check to see how much storage capacity I have used?
2. If I am well within my 2 GB limit, how do I resolve this issue of being unable to upload documents to the account?

Bob Delaney
Mississauga, Ontario