Ok, here's the story. I found out I was having twins at 10 weeks through u/s (as it was a natural pregnancy). The membrane between the two fetuses was very thin and hard to see. See pic below. The pic isn't the greatest as they gave me two of each baby instead of both on the same pic. However, you can see Twin B on the left and part of Twin A on the right. No membrane is visible on the pic even though there really is a very very thin one.
My OB/GYN told me she saw one placenta and thus we were expecting identical (mono) twins. I have been seen by the hospital high-risk pregnancy dept every 2 weeks since then to ensure no TTS was happening. Howevever, during my 16th week of pregnancy, I saw a new doc at the hospital who now says he thought he saw 2 placentas. I saw him again today (at 21 weeks) and he's convinced there really is 2 and that they are fraternal. I'm super confused as originally, they were telling me they were mono (due to one placenta and a very thin membrane), but now this other doctor comes along and tells me there is two placentas and the odds are 75% that they are fraternal. I myself feel that they are identical due to the fact they the membrane between then is so thin (I have seen u/s pics of fraternal twins and the membrane is much much thicker than mine). I'd really like to know your opinion on this.
Also, is it really possible to have 2 placentas, and a very thin membrane dividing them, making them fraternal? Thanks for your input in advance :)