The idea of being a CA3 in this position is self-contradicting. I don't think they would hardly let you in the heart room if you cannot intubate.
The student surely shouldn't let these miniscule (sp?) experiences in any way shape their career choices. However, as a side note, someone once told me about an article that found that a lot of people were drawn to specialties that they felt the the MOST inadequate at knowledge or skills-wise, hence you have cardiologists who weren't exactly heart whizzes until they finished.
the idea of someone being 'born for the specialty' is rarely the case. Somehow, magically med students assume that if they were 'destined' to be an anesthesiologist, they would get the airway on every single attempt, and if they miss even one, they eliminate themselves from being an anesthesiologist or whatever. If that were true, I would not be in a gas residency. Honestly, I was fully matched into gas, and into my intern year (just several months ago) before my confidence with intubation was any better-the more you try, the better you will get.
To the OP-You will be fine-keep trying!