Looking again at the Mar 18th baptism, the register carries the additional information "Born 28 Oct 1823". Don't know if that helps or hinders.
I do agree that even now having corrected the burial dates, you are still missing a baptism - if one occurred. A number of possibilities come to mind:
1 - a clerical error at the time (two burials registered when only one occurred. This might have something to do with the father's occupation, stated as "mariner" on the baptism register. Perhaps he wasn't around in March?
2 - Burials with age marked as "Inf" (infant) can imply still birth or death immediately on birth. I have seen cases where this results in a prompt burial / baptism ceremony and no baptism recorded in the register.
3 - The child was baptised under a different name. Perhaps the mother's maiden name if the child was illegitimate, but buried under the mother's later married name.
4 - The baptism was in another parish. Have you checked all the surrounding parishes? I did look on familysearch.org, but that didn't help. But they might simply not have all others transcribed.