Sores in the mouth have many possible causes. With multiple, simultaneous lesions (which is what I think you are describing), garden-variety aphthous stomatitis (canker sores) does not seem particularly likely. Various viruses can cause it, most of them totally non-serious. However, this isn't my area of expertise. HIV does not sound likely, and the risk of acquiring HIV from only a few episodes of vaginal sex is low, especially when some of them were condom-protected. But of course this depends on risk factors in your partner; the risk would be higher if her were an injection drug user or bisexual, for example.
You say you have "all the signs of HIV", but you don't describe fever, skin rash, symptoms of opportunistic infections (pneumonia, certain kinds of meningitis, many others), severe recurrent herpes, generalized lymph node enlargement, and all the other many symptoms. Few people with HIV present with only one group of symptoms, and mouth symptoms alone are unlikely to be due to HIV. Coated tongue doesn't mean anything; many things cause it (viruses or diet changes, for example), all of them much more common than HIV.
But why are you even asking theseuestions? The way to know about HIV is to be tested for it, not to try to work out the meaning of nonspecific symptoms. To answer your specific questions: 1) Low risk; see above. 2) I doubt your oral symptoms are due to HIV, but stress alone won't cause sores in the mouth--so that's not the sole explanation. 3) CBC is a general health screening test that never provides strong evidence either for or against HIV.
Bottom line: Although the likelihood you have HIV is very low, since you are concerned you should discuss it with your health care provider and decide together whether to be tested for it. The negative result should ease your mind.
Good luck-- HHH, MD
Then send an email to customer service instead of posting it on here.
This is how it showed up on my statement:
"MED HELP INTERNATIONAL 321-733-0069 FL"