"I have read that in new relationships, transmission is most likely to happen in the first few months of being sexually active… Is that true, and since we have been so sexually active for over six months, are the chances even lower going forward? Like I said, I am on the Acyclovir Regimen and never miss a pill."
I've not heard this stat, but I'd wonder about the variables - symptoms, suppressive therapy, condom use, etc.
"Does the presence of pubic hair really help prevent transmission? I shave completely, he does not shave at all…"
Pubic hair is thought to keep bacteria and such off our skin, but the real issue here is irritation from shaving. Irritation to the skin could, in theory, trigger shedding, increasing the chances of transmission. However, if your skin is smooth and there's no razor burn or whatnot, this probably wouldn't increase the chances. If he shaved, the breaks in his skin, if he was irritated, could increase transmission. You're on suppression, too, so that will help.
"The only outbreaks I have had have been on the outer labia… I’ve never had any inside my vagina. Does that mean I only ever shed externally? Does never having outbreaks inside my vagina make it less likely to transmit through vaginal sex to my male partner?"
No, you are shedding from all the mucous membranes in your genital area - the labia, the vagina, anus, etc. You don't just shed from where you get outbreaks.
"I have read on other forums that transmission will eventually occur in long term sexual relationships where one partner is positive and one partner is negative, no matter what precautions you take. But then I have also read many stories of people in long-term relationships who never gave it to their partner. What should I really believe?"
Believe that transmission is possible, and it's also possible to never transmit it. Believe that your partner is a grown man who is capable of making his own decisions regarding his body, the risks of sex (with you or anyone else), and that you can trust when he says he's okay with the chances he is taking.
"Lastly, I am female and acquired this from a male...Yet from everything I have read, it seems as though transmission from female to male is mostly unlikely, even with no protection whatsoever. If it is mostly unlikely, how could who I got this from have transmitted it from a female? It makes me very scared that if he was able to get it from a female, that I could give it to my partner no matter what precautions I take and I hate constantly worrying about that."
"Mostly unlikely" doesn't mean "can't happen", and obviously, men are getting this from somewhere, and not all men are only having sex with other men. The chances are lower for female-to-male transmission, for sure, but not impossible.
The key thing here is that at some point, you have to let this go. Your anxiety over this implies that you don't trust your partner's capability of making his own decisions (though I suspect that isn't true, but it does imply it), and that you don't trust the relationship to withstand transmission, or your ability to cope with it if he does get it.
Oh and you don't need acyclovir 3x a day. The dose is 2x a day.
You can still transmit the virus to your partner even without symptoms, have you disclosed your status to him?
If you want him to be completely safe then always use condoms and never have sex during outbreaks