How does one ask for a second test?

As you know, I've been diagnosed with partial seizures, mostly simple partial but some complex partial. I had one 20 minute EEG, which came out normal. I had an MRI, which came out normal except for a tiny 2.6mm cyst on the right side (the neuro was really specific as to where it was, but I don't recall what he said). Nothing in my test results indicates a cause to the seizures, and I want to know if there is one. I came off the Keppra two weeks ago, but we're going to try it again. Is it appropriate to ask for a second EEG? A longer one? I'm not sure I want a vEEG, but I wouldn't mind undergoing one for longer than 20 minutes. I want to know where the problem is coming from, and my neuro hasn't suggested looking into it. I know that the same brain can produce both a normal AND an abnormal EEG, since my oldest sister has had both. Redoing an MRI would be useless, since the one I had was a fairly high resolution one. Would I talk to my Neuro or my family doc? Do I wait for my next appt (Sept. 8) or do I call and ask? My neuro was really behind today and sort of rushed me out the door. Stupid me, I forgot my journal of what seizures I had and when as well as my list of things to ask.