You mentioned "leaking semen" with your first girlfriend. It could be "pre-cum" a natural lubricant some guys, not all (and some women) produce. Is it possible that in and of itself psychologically made you feel you had PE problems, and it went from there due to performance anxiety?

Just a thought. Best of luck to you, I'm sure that would be a very frustrating problem. Maybe a sex therapist could help, too.