In comparing the 1850, 1860, and 1870 census, I think that the Catherine that is 5 months old is Nancy Catherine, daughter of Caswell and Charlotte.I also believe that Catherine Aily, listed as 85 years old, is the mother of Charlotte.
There is a three year difference in the above census ages with most of the children.I tend to accept the earliest birth year that I can find. (Since this child was 5 months old in 1850 I accept 1850 as her year of birth)Most of the time, as the years pass, folks either get older fast or younger fast. I also think ages given were guessed at a lot by whomever was giving the information. One thing that was consistent in all the census was the order of birth of all the children.