There isn't a set way to do this, but here are some suggestions:
Ask some of your overweight friends who they see as a doctor, especially women who are large and pregnant or have children. This may lead you to a good OB/GYN, which is a reasonable place to start infertility treatment, even though a reproductive endocrinologist is desirable (that's the real infertility specialist).
Compile a list of infertility doctors. You can get names from your local Resolve chapter as well as from friends and people online. You can also check the List of Fat-Friendly Health Professionals at
http://www.bayarea.net/~stef/Fat/ffp.html (if you have a good doctor, please consider asking to have him or her added to the list to help other BBWs).
Other Places to Look for Doctors:
http://www.socrei.org/
http://www.ama-assn.org/aps/amahg.htm
http://www.inciid.org/directory.html
http://www.doctordirectory.com/Docto...ry/Default.asp
Once you get the names, phone numbers and address, decide on your next approach. Your options are:
Make an appointment and see what happens. If you do this, try to set it up so that you will meet the doctor fully clothed. You don't want to be undressed and feeling vulnerable.
Call and ask to speak with the doctor or one of his nurses. Be blunt and ask about the doctor's feelings toward treating large women. If there is any hesitation or doubt, keep calling around.
Write to all the doctors on your list and explain your situation, including your weight (be honest!). Ask if s/he would be willing to help you find out what is wrong and then help you to get pregnant. Not all of the doctors will respond, but most likely you will find someone who will treat you with respect and really want to help you.