High risk twin pregnancy/one baby had a velamentous cord Inseration anyone have this happen?

Melinda • I'm a 29 yr old, & engaged, I had B/G twins born 7/30/15 @ 33 wks. I also have a son 8 & daughter 6 yrs old ❤️
This is my 3rd pregnancy, I'm 16 weeks 4 days/due sept. 17th expecting twins, a boy & a girl. My last ultrasound was at 13 weeks 6 days, & the doctor told me that baby A's (girl) cord isn't inserted in the right spot, so will need to give me a ultrasound every 4 weeks to monitor her growth. That's all that was said, & I didn't know what the complication is called until today. I had my regular prenatal appt today & asked the doctor what it's called & what it means. He said it's called Velamentous cord insertion, & he didn't seem to concerned, just that they'll be keeping a close eye on it, & I'll be getting a lot of ultrasounds. I researched what it is & am freaking out!! I'm really scared, I've been nervous as it is carrying twins, & worrying about if something was to happen to them, or preterm labor. This worries me even more, it said stuff like growth, the baby could be on the smaller side, or if it ruptures it could cause the baby to hemorrahage, or still birth!! Anyone know anything about this, or have had it happen & their baby/babies be ok?