Hi,
I agree with Andie you must tell your doctor! I would ask the surgeon if you could postpone your surgery untill next year sometime. Being pregnant during and after surgery is quite dangerous because of the anethisia and rapid weight loss. The lack of nutrients and energy after surgery is why most surgeons recommend pregnancy only after 18months or more. I understand that your in a horrible position but it has happened for a reason so be a mum first then get the surgery afterwards! I hope this all works out well for you.
Vicci x