Twin weight difference

Sapphire

So I'm 24 weeks and 5 days today and I'm having identical twin girls. I was told today that they are concerned because baby B's weight is 8oz different then baby A's. This is my fourth pregnancy but first successful pregnancy and I'm scared because I want both my girls to be okay. I don't know if it's something I'm doing wrong or what but I want my girls to make it. I'm wondering if anyone is going through this as well.