Maternity bra

Melissa • First Glow baby in December 2016, just found out I'm pregnant again and due in March 2019.
So I'm trying to order a maternity bra online. I was a DD-DDD prepregnancy, but by the halfway point, I was at an F. I haven't expanded anymore, but obviously, I will when I'm breastfeeding. How do I know what size to order that will fit when I'm breastfeeding?