Possible momo twins!

Taya • Mommy to Elliotte: 7/9/17 💕 And Killian 3/10/19 💙
UPDATE: As of today (9w5d) we are back to a singleton pregnancy. We don't know when the other was reabsorbed, and while it seems sad, we are thrilled to have one very healthy looking baby! My doctor said this was the best outcome for the baby and myself: if we'd had the momo twins I would have had a very conplicated pregnancy and would have been in the hospital (a bigger one, farther from home) from 20 weeks on. Bittersweet news, but focusing on the positive, and I'm looking forward to a healthy pregnancy!***
So on Monday I went in for my 8 week appointment and was thrilled to find twins! My doctor told me not to get to excited: one is measuring a week behind and could likely be absorbed my vanishing twin syndrome. The other concern is that they appear to be momo twins, sharing the same sac and everything. I've heard this type of twins is often misdiagnosed and a membrane between them can be found at a later scan. I really hope this is the case for us! If they are truly momo twins this will be a very rare and high risk pregnancy. And it's my first!
My questions for you ladies:
1. Did anyone else have one twin measure small at first but still make it?
2. Did anyone else think they were going to have monoamniotic twins but later find a membrane?