baby cockatiel

my female laid 3 eggs, on 4th two hatched and on 7th 3rd hatched, that evening she died, frind feeding the day old one because dad didnt, he was feeding the others but on 14th one died, the one left had very swollen tummy and you could see seeds in crop. started hand feeding to clear this issue up, it made it but at 22days old, active, walking, eating 4cc every 4 hours, small crop wont hold more at this time, has very slow start of feathers but mostly bald, the other one hand fed from birht is twice that size and has lts of feathers, will mine just be slower at growing because of its near death beginning, I am keeping it warm,covered, holding once in awhile, bonding to it,and doing the best I know how. this is first for me, my friend has done this for a very long time but doesnt have a answer