If you read our read before posting post on this forum you'll see that we request you keep all your questions in your original post. It really is quite helpful so that we can best advise you and don't keep repeating ourselves.
The answer is, you probably will never know. At your age, 60% of folks have hsv1 already. It's too late to get answers to questions as to what else could it have been too at this point. You know you have hsv1. you know your partner has hsv1. That's all that's really important at this point.
grace
Have you been seen by a doctor? Even if it is possibly any of those things you mention (yes, coxsackie does have those symptoms and can occur in adults), you clearly need to be checked out by your medical professional. The web is not a replacement for that.
Being "doomed" to getting cold sores is much better than truly disabling or life-threatening diseases. For goodness sake, about 70% of the adult population have oral herpes! It's just a pesky skin condition!
Lastly, get tested if you want to know your true herpes status. An IgG type specific blood test (and a swab/culture if you have active lesions) is what you'd want to be accurately tested.
Echovirus perhaps? Herpangina? Anyone??