Epilepsy and Benign Myoclonus in Infants

Our daughter presented at 6 months with 'cluster' seizures; an EEG recording revealed an asymmetrical right-focal 'abnormality.'We were sent home and told to give her Frisium whereupon her seizures increased.
She was later diagnosed and treated for Infantile Spasm (IS) for 4 months with Tegretol and Vigabatrin.
Her MRI, CT, and development are all normal (no regression).
These drugs did not work either, she was readmitted at 10 months and found not to have ever had Infantile Spasms. We learned that the previous diagnosis was solely made on a Clinical (video) basis, with no abnormal recording on the EEG. But she did have a Right Focal abnormality that we've only seen manifest 3 or 4 times (this event was recorded). She is now being treated with Valproic Acid and our hypothesis is that the Myoclonis (She presents as if she has IS) may be benign and the Valproic does help the Right Frontal. But Our Doctor still believes that when our daughter presents with these Spasms, the only reason we don't see them on an EEG is that they are too deep in her brain to record.
She had another MRI at 15 months  that was normal.

My question is: How can we know that she has benign form of this epilepsy? She is now 17 months, slightly 'delayed' depending on who you ask, and only because we believe she's been treated with the wrong drugs. She has more seizure with level increases and drug changes. Her Dr. now wants to try Keppra with more on the 'list.' How can we do what's best for her if we still don't know what she truly has? When is enough?

thank-you for offering your thoughts,
sincerely,
matt.