The most current information on the risks of gestation age show that even up to 39-40 weeks, there are increased risks for problems including respiratory problems, jaundice, and even more serious problems (although at a much lower rate). Each week earlier that an infant is born means that the risk for complications rises.
Although twins are generally born earlier, this does not mean that they are more mature at an earlier gestational age. At any given gestational age, their risk for problems is actually higher than for a singleton pregnancy.
I'm sorry that I cannot help you plead your case, but I agree with your obstetrician that (all other factors being equal) a later delivery is better than an earlier one.
I have to agree with the doctor here.
Most planned inductions and C/Sections will not be scheduled prior to 38-39 weeks of gestation.