My little runt is still small, but feathering out great. Much better than yours, I was shocked by the photo comparison.
What about trying hard boiled eggs for extra protein? That might boost feather growth.
Are you sure she's still all fluff? Check her chest, wings, head, and back for pins. Okay, maybe not the head, since that grows last. It might not be too obvious at first, but once the pins come in, she'll feather out quickly.
Give her time.
I got my EE from the feed store with another EE, a BR, and a RIR on March 20th. The BR is looking like a roo and the RIR died, but that's not the point right now. When we got them, the EE was just the same as the others. Right now, she's grown a bit but barely at all. The...