No one says you have to be certified with anyone to offer CBE, or even doula services for that matter. :) As a doula, you should have a wide scope of knowledge to share with parents, and creating your own classes might help you realize gaps in your knowledge and help you fill them. I say if it's something you want to offer, go for it!
I'm training to become a birth doula also! (through DONA).
Its my plan that once I become cert; I plan on offering childbirth classes in both private and group settings. I also plan on teaching childbirth classes for children in both private and group settings. It is my hope to be able to create a support network for every mother and her family so that once I'm out of her life she will have back-up supports. Even though I'm not a childbirth educator I can still offer my services.
I'm happy you've chosen to take this route also.
I want my job as a doula to support my family, so offering classes in the daytime or at night is an excellent income supplement!
I should mention that I currently have two other doulas who I will be working with in this aspect of our career.
We will just be splitting the overall additional income from these classes.)
They are also my back-up call-ins if a birth is unusually long. I'm hoping over time to be able to have a rapport with all the doulas in my city, but the two doula's I do know are starting up this fall also so they are my inital contacts.
I hope these open a couple ideas for you!
Oh, also at your classes that you offer... If there is something you do not know the answer to, you can have a mini-whiteboard with you in class, and you can write down the questions to be discussed at the next class. I'm a CEA (education assistant) and this is a technique I've noticed teachers use.. Some call it the hover-board).