Hello,
I felt the same way. The first few flights, I was super nervous, thinking I suck. But then I realized that the student sitting next to me knows nothing, and is soaking up everything I say and demonstrate, just like a sponge. And after a few weeks it started to get so much easier. You get more relaxed and you pick up on things that you haven't paid much attention to when you went through training. Everyone learns different, and is making different mistakes.
The first time I sent a student up for a solo, I was more nervous than him, couldn't sleep for days. But when I watched him take off and fly around the pattern, and that smooth landing, I was so proud.
I absolutely love instructing and you will too. Just remember, your student will watch everything you do because you are a role model for them and they want to be you.
Pat