Why am I so rubbish

I have my incubator set at 37.5, the humidity is around 35 -40 during incubation, when pipping 60, I transfer my chicks ranging from 15 to 45 into a small brooder 2ft x 2ft, for 3 -4 days until I know they are all feeding them transfer to a larger brooder 3ft x 5ft, heat lamp at either side, feed on chick crumbs for 4 weeks, then onto growers and gradually raising the heat lamp until they are completely off heat at 6 weeks, then tranfering outside.
This can vary depending on outside temperatures, the colder it is the longer I keep them indoors.