I missed the fact that you also were tested at 3 months. Absolutely you do not have HIV. Rather than a GUM clinic, see your regular GP or other primary care provider.
Reacting only to the opening line, before I read anything else: Even unprotected oral sex is virtually zero risk. With a condom, there isn't any chance whatever of catching HIV. It doesn't matter what I am going to learn as I read the rest of your question: Either you don't have HIV or, if you do, you caught it somewhere else.
Now I have read the rest. Guess what? No change in my reply above. On top of the low risk of the event itself, in industrialized countries HIV is rare in heterosexual women who are not commercial sex workers, injection drug users, or immigrants from countries with high rates of heterosexually transmitted HIV (and not all that common even in them). (I'm not up to date on the situation in Ireland, but I'm pretty sure this generalization applies in your country.)
Finally, your symptoms don't sound at all like HIV. You should see a health care provider to learn the cause, but I don't speculate on this forum about the innumerable non-HIV possibilities in situations like yours.
Depending on where you live, you may have access to a genitourinary medicine (GUM) clinic. That would be an excellent source for expert care and reassurance about HIV, including repeat HIV testing, if they agree it is necessary. However, my view is that you didn't need HIV testing at all and still do not. But follow your own health care providers' advice about it.
Good luck-- HHH, MD