Congrats on your pregnancy! I, too, just found out this week that I'm expecting twins....but I am 23 weeks pregnant! Major surprise for me and I'm still trying to wrap my head around it. We also have another child, 3 yr old daughter.
So, some general info about twin/vbac/breech birth in AZ: the El Rio Birth and Women's Center are not currently legally allowed to attend any of these types of births and neither are home birth midwives. It's a huge bummer. I was doing concurrent care between the Birth Center and my home birth midwife Amy Zenizo (who is wonderful, BTW). My goal was to get my tests done with the BC for insurance purposes and stop seeing them at about 28wk and switch over fully to Amy's service and have her attend our home birth. BUT now I have to find another practitioner due to there being two babies. I'm mourning the loss of my home birth and trying to come to terms with another hospital birth.
Several people, including my midwife and a friend of mine who had twins and is pregnant with them again, recommended Dr. Maciulla at UMC (University Medical Center). I have yet to meet him (appointment is next week), but have been told he's the #1 go-to option in town for natural birth, breech, even in twin situations. I have also been given the names Jennifer Reinhart at Crossroads OBGYN and Jessica Moreno, also at UMC.
It might also be a good idea to get in touch with Nancy Capo. She's a Bradley Method instructor here in town and has had clients with twins before. She might be able to give you some direction, too. Her website is http://www.yoursnaturally.net/
Keep us updated! If you want to message me, feel free!