Welcome to the forum. I'll try to help. The bottom line is that most likely you did not catch genital herpes.
The first thing for you to understand is that the chance of catching genital herpes from any particular sexual encounter probalby is under 1 in 1,000, maybe much lower than that. You don't know your partner has herpes -- but statistically, she probably doesn't. And among monogamous couples in which one parter has genital HSV-2 and the other doesn't, who have unprotected sex an average of 2-3 times per week, the infection is transmitted in only 1 in 20 couples per year. And you had condom-protected sex, so that drops your chance of catching it by another 90%.
Herpes can't cause symptoms sooner than 2-3 days after exposure, so the chafing cannot be due to HSV you caught during the first sexual exposure you describe. And you are correct in assuming that when herpes is transmitted despite condom use, the initial symptoms should be expected in an area not covered by the condom.
As for the last question, no, this does not sound typical for herpes. Raw "chafing" is not usually the way herpes starts -- and as I said, you can't get herpes symptoms so quickly. That said, I don't know how to interpret the especially tender "spots". If those are blister-like or pimple-like lesions, or open sores, I would be more concerned about herpes.
You don't say anything about your partner. Have you spoken with her about your fears and concerns? It would be reassuring to know she believes she doesn't have genital herpes. It might be a very rewarding conversaton, especially if you don't know her well; you might find she is just as worried about STDs as you are. Statistically, of course, women are at higher risk for STDs from their male partners than the other way around.
Bottom line: I doubt you have herpes, but of course no distant online information source can guarantee anything. Since you are concerned, it wouldn't be a bad idea to visit your local health department STD clinic or your primary care provider for examination and testing. And have a chat with your partner.
I hope this helps. Best wishes-- HHH, MD