Break throughs in lessons!

So during my last voice lesson I had another break through yay! We were singing through To a Wild Rose and Dr.Hepworth was telling me to let the sound out of my mouth. She kept telling me to throw it to the wall, and somehow all of a sudden I just had this awesome, full, really nice sound come out! It was super weird and it felt really really good. I'm really not exactly sure what I did to do that, but I was able to do it a few more times after that. It was really exciting to have a sound like that, and I was really just more shocked than anything. Since I've been practicing after that lesson it's been kind of difficult to find what I did. Sometimes I can do it again, but sometimes I can't. I'm not letting myself get frustrated because I know if I do that then it just won't happen again. I'm feeling really anxious about NATS this coming weekend. I feel really confident with O Cessate Di Piagarmi, and especially so since I'll be singing that on recital this Tuesday. However, To a Wild Rose is making me a little nervous. Holding the high notes just  freak me out. Dr.Hepworth told me I don't have to hold them the whole time, but I don't want to take the easy way out. If I'm going to perform the song, I want to perform it well and by doing it the right way. But I've still got a few days to figure things out, and I know it's going to be a really awesome learning experience no matter how things turn out. Now I just have to pick my outfit out! If I don't sound good then at least I know I'm gonna look good.