Что делать с ненадёжной няней: стоит ли увольнять помощницу?

Mommy delimma... Another case of wwyd ...

So I've been struggling bad with postpartum anxiety and just getting the hang of having my three kiddos. Their ages are a big factor but there's nothing I can change about that. My sweet and understanding husband has offered to get me help (yes, even as a stay at home mom). I have a housekeeper coming biweekly now and was trying to hire a mother's helper for the afternoon /evenings before hubby gets home(just started a new demanding job and a longer slightly longer commute). My kiddo is 11 and has more homework than ever and she needs help. She also has extra curricular activities she needs rides to. My 3 year old is just living her best life but she's high energy, doesn't nap, and likes to play, the baby is my Velcro kid that's currently teething. It's a mess from 3-6:30 around here.

Anyway, I hired my oldest old babysitter weeks ago as a mother's helper. She was supposed to start after the new year but came down with the flu. She stayed away and pushed it back a week but the flu is brutal this year and pushed it back another week... So now she's technically 2 weeks in but I'll show grace because she was sick. She just told me yesterday evening that she won't be able to work most Wednesday evenings because she has class... Which sucks because that's my husband's definite in office day and sometimes has late dinners with clients. I said okay I'll see you tomorrow. She texted me an hour ago and told me she's having a bad day and asked if she could start tomorrow instead. Like wtf. She's 20 years old and a friend's daughter which is why I'm hesitant to fire her before she even starts but like damn she's annoying lol. I just need reliable help 😩.

So would you fire her??