" read that if I contacted genital HSV1 from my girlfriend through oral sex then there is a good possibility that I did not ever have any form of HSV1 before that."
Correct - the vast majority of folks who contract hsv1 genitally only contract it because they didn't have hsv1 orally first.
How were you diagnosed as having hsv1 genitally - lesion culture and typing? Has your gf been tested for herpes or does she have a history of hsv1 orally?
" Is it possible for me to not have oral HSV1 and have genital HSV1 even though we kissed way before we had oral sex? "
Unless you get an obvious cold sore to know that you do also have hsv1 orally there's no easy way to determine this. We don't have good studies on how many folks contract hsv1 both orally and genitally at the same time but from the few that we do have that only looked for obvious cold sores - about 1/4 of folks at least get it both orally and genitally. As long as you are with your current partner it's not an issue if she has hsv1 orally but should you ever have a partner who doesn't have hsv1 - then it's worth talking about even though you aren't sure if you have it just genitally or both orally and genitally.
"Also, how likely is it for GHSV1 to be transmitted to other parts of my body? I only ever had one red mark on the base of my penis that then crusted over and now is just red and a little bit inflamed. Is it still as contagious as with an open herpes sore"
Once the initial ob is healed it's not likely that you'll transmit it to other body parts. Just like mom always told you - wash your hands after using the bathroom or touching your genital skin.
You should wait until your genital skin has returned to normal before resuming sex with your partner. If she has hsv1 orally she has significant protection against contracting it genitally from you but err on the side of caution and wait for this to heal completely.
grace
Yes, if you contracted HSV-1 genitally from your girlfriend, then you never had HSV-1 antibodies so you didn't have it before that. Yes it's possible to not have oral HSV-1 even after kissing her because you might not have kissed her while she had 1) active lesions 2) viral shedding.