Mirth is just...
...it's an unusual word in modern language.
I think, other than that, it's okay. I just notice it because it's unfamiliar.
I just didn't like "shades of pink" because it's too close to "rose tinted." But if since you've used it to tie in with other ideas then I'd keep it.
There isn't anything seriously wrong with this poem at all. And, you're right! You can't write poetry. I was just trying to be nice.