My question is am I at risk really at all for any std or sti? And by taking the azithromycin as prescribed am I all but worrying for no reason?

Oral sex is safe sex:  not entirely risk free, but with a far lower chance of STD than unprotected vaginal or anal sex. For mouth to penis transmission, some STDs are extremely low risk, close to zero (HIV, chlamydia, HSV2, HPV, viral hepatitis); and others are more common but still unlikely for any single exposure (gonorrhea, herpes due to HSV1, syphilis, nongonococcal urethritis).

I would have recommended against antibiotic treatment; but if done, azithromycin is not a very good choice. Also, you're on the wrong dose for STD treatment or prevention:  a single dose of 1 gram (four 250 mg pills) is the only recommended treatment for any STD. However, even this is reliable mostly for chlamydia, for which you were not at risk, and not reliable against any of the others. That said, 250 mg daily for a week probably would prevent chlamydia and perhaps NGU and gonorrhea (and maybe syphilis) -- but this dose has never been studied for this purpose, so we can't be certain about its effectiveness.

In summary:  there was little or no risk from this event, and the antibiotic really not necessary. However, now that you have started it, probably it makes sense to complete the treatment; or take 4 pills at once and discard the rest.

I hope this has helped. Let me know if anything isn't clear. Best wishes--  HHH, MD

But if you need maximum confidence you couldn't give her anything, you would need a urine gonorrhea/chlamydia test (which could be done at any time); syphilis and HIV blood tests in 4-6 weeks; and an HSV1 blood test now and again at 3-4 months. And you could never be 100% certain about HPV, although that probably doesn't matter since everyone gets genital HPV anyway.

That completes the two follow-up comments and replies included with each question, and so ends this thread. Take care and stay safe.