You have to remember, battery life is highly subjective. Settings, applications and overall usage greatly varies. It's difficult to have an accurate metric for battery life.
Based on your usage from just the top 3 things, I think you are on par. YouTube takes a lot of power. Plus your background usage for YouTube is insanely high. Try closing out the app when you are done.
Actually nevermind, I've had my iPhone plugged in so the Youtube data etc isn't correct. It would be much less usage of those 3 apps for the 21% battery I had when I posted this.
I made a genius appointment, although I hate having to go tbh
Yeah I’m getting about a third of that. 12hrs just sounds like another universe at this point lol. I don’t see it happening unless there really is a severe defect with my 8.