twins size difference risky?

I'm 14w4d one twin has always been smaller from the get go. I think when I ovulated, the second-smaller egg was fertilized right after the main egg. (clomid + ovidrel) 2 sacs, smaller baby has a smaller sac

Baby caught up by 9 weeks and at 12 weeks, he was 1.3cm smaller. Now he's by 1.6cm.

through the Chromosomal blood test, everything came back good.

My OB seemed a bit worried and I'm seeing a specialist tomorrow to determine if the twin is at risk.

Anyone else has had this and everything turned out well?