Syphilis, herpes type 1 and 2 gonorea and non specific urethritis(inflammation of the urethra caused by the normal bacterial flora of the mucosa in the mouth). These above are the risks of the short unprotected encounter, though based on what you are saying they are quite low. If she didn't had any open soars on the mouth or tongue, then it is unlikely to catch syphilis or hsv2, type 1 with the popularity of oral sex is found very often in the genitalia but rarely causes any problems.
Yes, the protected activity is the safest it could be, though nothing is 100% safe.
That said, I agree 100% with everything klamidia said. Wouldn't change a thing.
I wouldn't worry too much about this. If you start to see any symptoms, get checked, but with such a brief exposure, I'd be very surprised if you did.
When I asked of gono he said he'd never seen one case from receiving oral for turn into gono. He also said once tests were back and negative I could resume my regular activities my my significant other. I'm his opinion the testing wasn't necessary but did so for my piece of mind
They don't do urethral swabs much anymore - your doctor is correct. However, it was pretty early to test, though I wouldn't worry. You had protected everything, so you should be fine, even with the very, very brief unprotected oral.