Luckily, under the ADA, it is illegal to fire you for a disability. I don't know how the law works, but it seems that discussing this with your employer and seeing ways to make changes that you can both live with to accommodate this would help. Memory can be a problem, I found, from both the seizures and the meds. I was finally diagnosed in 1971, long before ADA, :-( . I should have bought stock in Post-It Notes! I write a lot down, and found that using writing, repeating back what I'm told (if it's appropriate to do so) and even just letting folks know it helps me to have things written is useful. So does a good sense of humor, and a lot of synonyms. I was 27 when my grand mal seizures started, older than when I was diagnosed with petit mals, and that's when the memory problems got really bad--the seizures at one point were so bad that my (now ex) husband said I recognized only my three little sons, and for awhile I had every woman's dream--a new closet full of clothes every day. That's because I didn't recognise them! I don't mean to make light of the memory stuff, my friend. I'm 65 now, and I can't tell a memory problem from a senior moment. Geesh!!! Hope this helps some, or at least helps you smile a little.
I have heard that memory loss can be a problem on a lot of seizure medication. I know that my brother-in-law talks about it. That might be something you want to bring up with your doctor. See if maybe you can get some kind of documentation about this problem. They can't fire you on account of a disability that's illegal.