New - still hard to believe!

I had a blacking-out episode this December which the doctors now believe was a seizure. I'm 35 and have never had anything like this before. Honestly, I still find it hard to believe except that my eeg results cam back abnormal, so I guess I have to believe it! Since then I have had a few auras but no passing out. My doctor started me on Trileptal. At first it made me really sick, so exhausted I could barely lift my head off the desk, and made my face break out like a teenager. On the upside, no seizures so far! I am not quite as tired after a few weeks on the drug, but still nowhere near my old self. Anyway, my question is, how long does it usually take to determine whether a AED will work for you? I feel like I'm just sitting around waiting for the other shoe to drop -- just waiting to see if I have any more seizures or not. It's kind of frustrating....Plus deep down I wonder whether I should really be on the meds at all...after all, it was only one seizure. Does that mean there are likely to be more? Thanks for your thoughts!