You could try this list:
http://www.cat-and-dragon.com/stef/fat/ffp.html
Alternately, I got to my primary doctor by asking my gyn to recommend someone. Do you have a good enough relationship with your primary to be able to ask for a referral to someone they know wouldn't be a jerk about your weight?
Remember that when you walk into a doctor's office, you may be a patient, but you are also a customer. You can call ahead to see if they have larger gowns and also specifically say that you request that your weight be kept confidential. Your doctor and his/her nurses work for you and should respect all of your requests.