I felt the same way when I got started.
You can work so hard for your student, pour everything you have into them, be as thorough as you possibly can be... and they might still come back the next week having made barely any progress.
It's enough to make you wonder if you have any business taking voice students at all.
But think back...
Remember how hard making decisions while in the moment of practice was when you were just starting out?
Wouldn't it have been nice to be handed a few sheets of paper that helped you recall your voice lesson and practically made a checklist of all the things you teacher mentioned in the lesson, plus reminded you to take notice of some things they didn't?
Give your students the opportunity to prove to YOU how great of a teacher you are!