Mono/di?

Siobhan • Saoirse Lynn 11/22/18 TWINS due May 2021

From my last ultrasound at 7 weeks, my Dr said my twins each have their own placenta, but it appears (since hard to tell off the pics) they are in the same sac. Tech wasn’t sure at the time of ultrasound either. We will confirm at my next ultrasound in a couple weeks. Dr is saying mono/di twins, but this seems to be different than what I see described in other posts. Any insight appreciated! 😊