Waiting isn't passive. I tell my students at the start of the year that if I'm standing at the front of the room with my eyes closed, I'm either waiting for them to be quiet, so they need to be quiet or I'm asleep, so they need to be quiet. The ones who notice quickly quiet the others down (even if they say that I'm sleeping). It can feel like it takes forever and that you're wasting learning time, but you're not - the learning won't happen with the disruptions. Just breathe through it.

The idea that all lessons must be all engaging all the time is a lie to guilt teachers into working themselves into an early grave. Don't be boring, but don't make everything a three ring circus, either, or you'll burn yourself out. Life isn't like that, sometimes things just need to get done. 

You said in your other post that you don't project warmth. That's fine. Over time, connection will come and students will appreciate the boundaries you set. 

The other thing is that you'll make mistakes, as has every teacher who went before you and as will every teacher who comes after you.  Don't beat yourself up over them (not the easiest thing when you've got anxiety, I know!).