Yup, it's 3,000 including spaces and punctuation. It really is limiting, especially if you have something pertinent to share that is kind of lengthy. However, you'll have a chance to expand on what's there in your secondaries, which don't really have a limit(but don't write a novel!). Start working on it now; write two separate essays. A shorty for AACOMAS, and if you start looking online you can anticipate the kinds of questions that you'll encounter on the secondaries, such as:
-Why are you applying DO?
-Why are you wanting to study medicine?
-What qualities do you feel you bring to xxxCOM?
-Why should we offer you a seat at xxxCOM?
etc.