It is not your fault. That is what I said in the first place to myself too.
I have Family Link by Google. That helps my daughers as I gave them 1hour and 1,5 hour on their phone. They need to install it on their phone as well as the parents. You can restrict each app for an amount of time they are allowed to use and even block it from their phone. Another feature is to block their phone too as they are too much on it. Hope this helps: https://families.google.com/familylink/
Great read, and I love you honest insight.