Switching to alfalfa hay was smart. Pregnant does need alfalfa for lactating.
My Luna is now on alfalfa pellets and I plan to keep her on them through her pregnancy up until weaning. Alfalfa usually makes bunnies plump, but kits do take a lot out of Mom, so the extra calories help.
Keep giving lots of hay and pellets. Give green but just watch them Some greens will give bunnies gas. And your does don't need gas while being pregnant.
And plenty of fresh water.
Also I'll be supplying my pregnant doe with lots of wheat grass. Supplies oxygen and trace minerals needed.
Hope this helps. Good luck with your does. Hoping for easy births and healthy kits. Please keep us updated.