Hi Kollegeqt,
I'm a little confused about what happened when. This is what I think you've said. You first had intercourse in March of this year and including that time, you've had 2 partners for intercourse: T and your ex. You had sex with your ex in September and had your first OB in November.
I'm wondering: Were you diagnosed from a swab culture? And was T. diagnosed from a blood test? A swab culture (they scrape the sore with a Q-tip type of thing) is about as accurate as it gets if it comes back positive. Blood tests are almost always accurate if they come back positive, although there are different tests available with varying degrees of accuracy.
Both blood tests and culture tests can come back with false negative results though, so just because someone tests negative doesn't mean they necessarily don't have herpes. A blood test should be taken 12-16 weeks after initial infection, otherwise it may not be able to pick up on the antibodies before they've built up in the person's bloodstream.
So if your ex was infected within 12 weeks before the test, he wouldn't necessarily show up as positive. He should get another test done in a few months, and to be sure it's a type-specific test. He probably got the POCkit test done, which gives very fast results, but is also somewhat less accurate than some others.
If T. tested positive from a blood test, then he was likely infected longer than 3-4 months ago. It is possible for someone to go for years without outbreaks or other symptoms, although he might get other symptoms he just never thought of as being herpes, like itching, tingling or burning in a specific area, flu-like symptoms, swollen lymph glands, etc.
If you were diagnosed from a blood test, then you might have had it before September too, in which case your ex especially needs to get checked out again after a couple of months (after that 12-16 week period).
I don't know if that helps or not. Herpes can be really confusing, especially because different people tend to get different symptoms from it. You'll need to do some reading about it, so you'll know how to protect a partner from getting it, or from spreading it to other areas of your body or your partner's. There are a lot of websites with varying degrees of accuracy and up-to-date information. Herpes.org (listed in this board's Resource Links) is a good one to start with.
Good luck! Feel free to ask more questions if you need to. Most of us aren't health professionals (including me) but we can share our infomation and experience and support.
TheOneInFour