Two white spots don't sound like cold sores, but obviously I didn't see them. They could have been canker sores, not cold sores.
You took the blood test too soon to see if you got it from the encounter, and the hsv1 IgG misses 30% of infections. There's a great chance that you already have it, as 67% of people under 50 have it globally.
I understand that you feel guilty over this, but this sounds like a bunch of worry over what might be canker sores, not cold sores.
If you haven't had genital symptoms yet, I wouldn't worry. You had protected oral sex, which reduces your risk significantly.
Well, you followed up with a clinic. They are really your best source of info. Oral herpes is not a big deal. 80 percent of the population. Children have it. You've had two negative blood tests. They don't lie if you took them in the proper time frame.