Oh, Eric's mama, I'm sorry. It's so hard when you try and do your best and then somebody doubts you. It IS confusing.
From Midwifery Today- http://www.midwiferytoday.com/articles/nutritionpreg.asp
The midwives I had and the midwives I've worked with (as an assistant midwife) all generally followed his recommendations (they usually recommended less milk/dairy products as they believe overdoing milk products can build larger-boned babies). OBs don't usually consider nutrition holistically. If your calories are real food- protein, whole grains, vegetables and fruits with some healthy fats- then you will not develop gestational diabetes as a result from weight gain eating those healthy foods. If you are gaining weight because you are eating cheetos and donuts or even "healthy" junk food, then it's true that you don't want to gain junk food weight. I'm also wary about you being defined as "overweight" because I don't agree with those charts!
My mother-in-law, who is 5' 2", carried her twins to 40 weeks, and they were born vaginally one and a half hours apart. They weighed 8 lbs 5 oz (boy) and 6 lbs 14 oz (girl). I have two friends who carried twins past 40 weeks (working with midwives) who followed Brewer Diet- all those babies were close to 7 pounds or more. I have two other friends who had twins with OBs who were induced at 37 and 38 weeks. One of the docs admitted that in their medical books there was no discussion of care of twin pregnancies past 37 weeks so he wasn't comfortable letting it go longer, citing something about being worried about the integrity of the placentas.
Unfortunately OBs don't seem to have an agreement/understanding about pre-eclampsia being pretty much a result of malnutrition. It's still considered a result of high blood pressure, which is really only a late and secondary symptom of pre-eclampsia. Even in People magazine recently, a Kardashian delivered early b/c of pre-eclampsia, and they cite it as a disease of high blood pressure. OBs are not required to take a nutrition class in med school, so no wonder there's a disconnect.
Do you have any other choices of care providers?
You might be interested in this too- http://www.spinningbabies.com/spinning-babies-and/twins
Also, check out this awesome picture of twins just born! Found it today when I was researching birth photographers- http://www.melissacatephotography.com/birth/