You are going to be a fabulous NICU nurse! Chubby babies are so hard and at such a high rate, it was bound to happen quickly. It sounds like you have great management behind you, and that you have learned from the mishap. I agree with above posters, never swaddle and IV limb. In my experience, it increases chances that the IV will go out sooner and like you said, you cannot visualize it well. You will get so good, that you will be able to quickly glance at an IV and know its out. But continue to feel and assess like never before. You've got this!