I'm still having trouble understanding your timeline, so I'll just throw out what I've learned in the months since I've had symptoms. I've become quite an expert since I've had to contact a few people and try to work things out.
The 75% chance you cited really applies to an outbreak with sores. That doesn't seem to be the case for you, provided you were having standard vaginal sex. Also, that number can't be too reliable, because you can't ethically create a study in which you have someone with a visible outbreak have unprotected sex with someone else to see what happens. So take that 75% as a rough estimate.
There's no reliable estimate for the chance of spreading herpes with shedding and unprotected contact that doesn't have blisters. My gut feeling would be that it would still be high but it is definitely less than 75%.
As for testing, about 65% of infections will be caught within 6 weeks, around 95% will be caught by 12 weeks, 99% by 16 weeks, and effectively anyone who would ever test positive will do so by 6 months. Pretty much everyone will eventually test positive, especially if we're talking about normal otherwise healthy people.