Hi Bran24, welcome to CWE!
Technically an epilepsy diagnosis just means that someone has had more than one seizure. Since you've had simple partials plus this grand mal, then, yes it sounds like you have epilepsy. (Were the partials diagnosed as such at the time, or this a diagnosis in hindsight?) The EEG is basically confirming what the actual seizures indicate.
Unfortunately, the fact that you feel fine and symptom-free now doesn't mean that you won't have a seizure at a later time. (I'm symptom-free right after having a seizure, often for months at a time; I have had over 20 grand mals when unmedicated.) You need to consider the risks of having another seizure (injuries to yourself and/or others), or the risk that your seizures might progress (as they did from partial to grand mal) when deciding whether or not to go on meds.
Meds are no picnic, of course -- often they are the lesser of two evils -- but for many they work fine, and the side effects are tolerable (as in my case). The thing about AEDs is that everyone has different experiences on them -- what works for one person may suck for the next. I might have Side Effect A, while someone else gets Side Effect B. I might need a tiny dose, while someone else needs a big dose, or more than one meds. I wish I could guarantee that your experience on Keppra would be perfect or even tolerable but there's just no way to do so. I know of at least 2 people on Keppra who are happy with it. And as you've no doubt read, it makes some folks miserable. The only way for you to know for sure is to try it and see. If it doesn't work out, there are other meds to try, or you can consider going med-free (Never stop cold turkey though, and always check with your doctor first).
If you decide not to go on meds, let your doctor know. And do your best to be proactive about your overall health.
http://www.coping-with-epilepsy.com/forums/f22/proactive-prescription-epilepsy-1254/ Avoid any known triggers, and if possible keep a journal so you can note any seizure-like symptoms.
An epilepsy diagnosis is extremely confusing. You're doing the right thing in looking for more info. I hope you feel free to ask as many questions as you need. CWE member can offer a lot of info, anecdotal advice, support, and empathy.
Best,
Nakamova