1. I am nearly 100% convinced I have contracted HSV-2 but would like to hear your thoughts on my symptoms.
I would say it is very unlikely that your acquired HSV 2!
2. Should my next step be to igg test at 6 weeks or can I do it earlier?
You can do it now and get a baseline result but if you are still concerned, you should do it again at 12 weeks out.
3. I keep checking everywhere for potential blisters/lesions. Would only the areas that were contacted break out? Or could they develop on my buttocks despite her never touching me there?
If you contracted it genitally, outbreaks could appear on the buttocks as a recurrence, but not as a primary infection, no.