You might have HSV 1, yes, but difficult to know for certain from your description. If you get it again, you should definitely go in and have someone swab test this sore using PCR preferably, to see. If the IgG is positive for HSV 1, you will know that you have it but you won’t know exactly how long you have had it. It could also be impetigo or angular chelitis, both of which can cause breaks in the skin in the corner of the mouth.
When you partner presented you with her blood work which indicated she was positive for HSV 1, didn’t you wonder about your own status since she had a test result for herpes and you didn’t? You could also have HSV 2 and not know it. Didn’t she ask about your HSV 1 and 2 status? I really doubt that someone would get an STD screening as a way of telling you that she gets cold sores – she could just tell you that she gets cold sores. A more likely explanation in my opinion is that she wanted to know about her own HSV 2 status and the lab routinely tests for both and she also wanted to know about your status, offering to get tested herself as a diplomatic way of asking you too to be tested.
I also think that the likelihood of having a positive strep test AND a new case of oral herpes at the same time is pretty unlikely, really. Your strep sounds like strep to me.
In my opinion, if a person has known history of either having cold sores (not canker sores) and/or is HSV 1 positive, it is a good idea to disclose to a new partner. Others may disagree. That’s what I would want to have happened to me when I was single so I apply that standard to others.