Lia, I am glad you are tweaking your husbandry. When the little one starts really progressing, it will be a joy.
On substrate, I would ditch the sand for both. I have been rehabbing beardies and other lizards for awhile and I frequently have to nurse animals through elimination of sand in the GI track, which is not easy. Impactions can occur even in adults, but especially in babies. I recommend paper towels for babies because it is easier to replace daily. In adult vivs, I use paper towels or tile.
There is something else that I have started doing that is not in beardie care sheets yet, but I hope will be. I also keep and rehab chuckwallas and uros, and they need high fiber content in their diets. Like beardies, they are also from desert and semi desert environments, so much of their diet in the wild is grass, both green and dry. Uro keepers have started using Zoo med grassland tortoise pellets, crushed and sprinkled on the salad to add fiber to a somewhat low fiber content diet that is based on store bought greens. Since I have so many lizards, everyone gets the same salad and the beardies have really benefited from this addition to their diet. Your little one needs fiber to help clear the sand out of its GI track.
Here is what I am talking about. I crush the pellets in a coffee grinder, then sprinkle about 1 cup to 6 cups of chopped salad, refrigerate overnight, and feed it the next day. The beardies as well as all the omnivore and herbivore lizards here have well formed poop instead of smears and watery stools, and they have great weight and are very active.
http://www.herpsupplies.com/product....03&id=SZMZM131
About 3 times per week, everyone also gets chopped squash, yellow raw and others lightly steamed. I would avoid chard. It binds with calcium and might prevent uptake of calcium.