I have chuachua and he has seizures too; but at first they were few and far between. Talked to the vet and he said the same thing that your vet did.
Then they seemed to be coming more frequently. So we took a whole month on a calender and dated and timed every seizure for that month. When they started coming more than one time a day was when the vet put my little Shorty on Phenobarbital one tablet twice a day. Sence then he has had only one seizure and he is doing great. I hope that this helps and your pet will be better soon.
tjb