I have one Egyptian Fayoumi that I bought late last summer to be company for a little EE cockerel someone had dumped in my yard. She was a well started pullet when I got her and hasn't changed much in size since then. I also have a Golden Campine that my daughter bought as company for another lone chick hatched here. The Egyptian and Campine resemble each other quite a bit and are definitely little, but I don't have enough experience with either breed to know what's out of the ordinary in terms of size. There are runts in every species, right? Your chick may be predisposed to dinky-ness and otherwise perfectly healthy, though optimizing her nutrition and keeping a watchful eye makes good sense.
So sorry about your losses :(