I was unfamiliar with misophonia so I went looking into it. I know it is a poorly studied issue, but I wasn't able to find any peer reviewed research where children's noises in general were used or reported as a trigger. I found lots of discussion forums, but that is anecdotal.

The reason I went digging is because the op describes all children's noises, happy, sad, whatever, whereas what I read in the literature was very specific noises were reported as triggers. E.g, lip smacking, chewing, pen clicking, etc. In one study, they even used videos of children and dogs playing to help participants calm down and establish a baseline. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0227118

While I'm admittedly ignorant, it seems OP may have a more general aversion to children than I would expect of misophonia given what I've read from medical sources.

I only mention this as a counter suggestion to help op avoid self diagnosing and maybe going down the wrong track.

I think counseling is warranted to help sort it out.