Welcome to the STD forum. The short reply: It is highly probable you have genital herpes due to HSV-2; the apparent yeast infection probably was your initial herpes infection; and your second (July) partner also is probably infected with HSV-2 and likely was the source of your herpes.
You can ignore the IgM antibody results, which are very unreliable in diagnosing HSV-2; and although in theory IgM is supposed to help distinguish early from late infection, it doesn't do that with any accuracy. Here is a thread that explains it. Although 4 years old, the information remains accurate:
http://www.medhelp.org/posts/show/248394
Your IgG test results are somewhat confusing, because you had a definitely positive result in July and apparently a negative result in September. However, that might be due to treatment with valacyclovir (Valtrex), which can delay positive results and sometimes might make a previously positive test turn negative again.
Dr. A is wrong in saying you were negative to start. Your initial test was unequivocally positive. Dr. B is partly right: both your blood tests were positive for HSV-2, but there is no such thing as being only "exposed"; a positive result means a person is infected with HSV-2. Dr. C's comments make no sense; visual diagnosis of herpes is much less reliable than laboratory diagnosis. To your specific questions:
1-3) It was probably a primary outbreak mostly because it caused diffuse genital irritation (which I assume involved both sides of the genital area, even though you don't say it) as well as the lymph node involvement. You can be quite certain you caught the infection 3-5 days (possibly as long as 10 days) before your symptoms started, and extremely unlikely you caught it in February. Recurrent herpes is rarely so severe and rarely causes lymph node inflammation.
4) EBV doesn't gential ulceration and lymph node inflammation localized to the groin. Also, you have no basis to assume your sore throat and "bouts of flu like symptoms" were due to EBV. At least 20 other conditions could cause the identical symptoms; and initial EBV infections (i.e. infectious mononucleosis, often called glandular fever in the UK) generally last no more than 2-4 weeks.
5) Nothing except herpes is likely to cause the symptoms you describe.
6) HSV-2 is more likely, but conceivably it was HSV-1. Apparently you were not tested for HSV-1. If you were, and can provide those blood test results, I can comment further.
7) Yes, that sequence of symptoms certainly could be herpes. It probably was.
8) Yeast infections (thrush) rarely cause open sores. Also, the treatments for yeast usually are very effective; that you didn't respond well to the initial treatment argues against yeast as the cause.
If you could provide more detail about your and your partner's HSV blood tests, I might be able to comment further. What brand of test? If HSV-1 was tested, provide those results as well.
Regards-- HHH, MD