Confused About First and Only Seizure

Hello! Okay, so I am twenty years old, and about a little less than a week ago I had my first seizure. I have never had a seizure before, and since then I have not experienced another seizure. I have no memory of the seizure, but I have been told that it happened something like this: I inhaled sharply and leaned back in my desk chair, and then I leaned forward and fell on the ground. Perhaps I should note that this is in the middle of one of my classes. One of my friends says I looked paralysed because my arms were still out in the position I had fallen in, and I was making noises and foaming at the mouth a bit. He says then I was silent for a while, and then all of a sudden I started breathing heavily (which might have been hyperventilating, but I don't know really. Eventually EMTs came, and apparently I was very confused and did not know where I was--something I do not remember experiencing. I have bits and pieces of memory from being taken out of my school and being put in an ambulance, but before that is pretty unknown to me. I do remember feeling like I was in and out of conciousness, and I remember people wiping off blood from my head, and I remember feeling like I had been woken from a nap and so I asked to be let to sleep. I split the spot above my left eye open, but it doesn't appear to be anything major. It only required four stitches, which I got out today. I also had a humongous swollen area around my left eye which eventually turned into what is now a black eye with broken blood vessels in the white part of my left eye or my sclera. I am sorry for the gargantuan exposition, but I just want to give as much detail as possible. Since all of that happened, I have visited the hospital for many tests. The day of the seizure I had a CT scan. Now I have had an EEG, MRI, and MRA. All of these have come back normal, but it leaves me unsure of why what happened happened. I am studying abroad in Jordan currently, but have adjusted extremely well and have faced no anxiety about the change. I am getting more sleep here than I do at home (in the USA), and I haven't been all the stressed out in general. I have been told that these are sometimes factors that lead to someone having a once in a lifetime seizure, but I do not feel like I have dealt with those. The only medication I am currently on is buproprion for general anxiety, and I have been on it for over a year (maybe about a year and a half). I don't know, I have the feeling that I'm being dramatic and making a big deal about it, but I just feel frustrated that no one can give me an answer as to why I had a seizure when my brain has shown as completely normal in tests. I was just wondering if someone had better insight into this issue because I feel as though it is never going to happen again, but I want to know why. Thanks! Gita