Jennibean, it is totally normal to feel like a klutz and to wonder if you picked the right profession when you’re new ( and even, on occasion, when you’ve been a nurse for years!) . We all did/do. Time and experience are the best teachers and confidence builders. I would strongly suggest you follow Jason’s advice and review a procedure with your preceptor out of the pts room. At that point your preceptor can get a feel for your understanding of the procedure and interject without throwing you off in the room.
Hang in there and know that every day of your nursing career you will either be learning something new, fine-tuning what you know, and as time goes on, sharing that knowledge with some new nurse who feels like a klutz!