Twin A measuring small at 20 weeks

Desiree

Mono/di twins. I went to a follow up ultrasound at MFM for watching cord blood flow to make sure no signs of TTTS. She says the amniotic fluid is great, she can see babies bladder and stomach well so it’s not looking like TTTS. She did say she is concerned because baby A is 20% smaller than baby B. Baby A is 9oz and baby B is 11oz. Has anyone been through something similar? My doctor started bringing up how there’s nothing to do to intervene besides delivery... she is saying the soonest to deliver for a viable birth is 24 weeks. She wants me to be monitored more and possibly be admitted to the hospital for monitoring if nothing changes.. I’m so scared...