I am 27 weeks with mono di twins. I have an OB and perinatalogist in charge of my care, and neither of them have told me c sections are preferred. Both prefer to try for a vaginal delivery as long as baby A is head down. My doctor may try to turn baby B if she is breech, but said I could try to deliver her breech if she won't turn and she's not in distress. I will be induced via pitocin at 37 weeks, as long as baby A is head down. My OB told me out of her last four mono di twins, only one had to have a csection.
I would get a second opinion if your wanting a vaginal birth. The fact that almost all dr like csections for mono twins is not true. Now if they are mono mono, that may be a different story, as there is much added risk if they share a sac too.
My twins, though not mono di, were born vaginally without any medical interventions at 39.3 weeks. They are fraternal twins and their placentas had fused by the time they were born. I know it is not your situation so all I can do is offer words of encouragement.
I would suggest that, if you wish to explore a vaginal birth, you get a second and third opinion. Check into your docs overall c section rate- if his is high then he may prefer c section over natural birth. Maybe you could find a doc that would help you achieve vaginal birth, but would be prepared for the c section should the need arise. Just remember that this is your body, your birth and your decision. Maybe look into hiring a doula to help your voice be heard during delivery. Have you looked into natural c sections? Some women are having baby placed immediately on their chest after delivery and attempt to begin nursing while being sewn up.
My twins shared a placenta- it ended up causing a few issues and I had an amnioreduction (drained fluid) at CHOP (Philly) they are WONDERFUL! Anyway- talk to your doctor and tell him/her what your wishes are. I was a c-section at 33 weeks, but I had been hospitalized bc I was previa. There are lots of factors, just make sure everything is explained to you.