That is scary. I actually wondered if I made that mistake last night, because I could not remember if I took my evening dose of Lamictal. I have to be super careful with Lamictal, because I am already on such a high dose, so I was panicking about whether I doubled up or not. I don't think I did though. I noticed a headache, but it could have been unrelated. I did check with a pharmacist once before about what would happen if I accidentally doubled my dose. They said I might feel the side effects more intensely, but they told me it would be rare to have such a bad reaction from them, but I still worry.
I can relate to being so nervous about doing that. These meds are risky. Now, I try to just skip a pill if I'm not sure, but I still sometimes take it and later second-guess myself. I need to get better at keeping track, although most of the time, I'm alright I guess.
I am glad that you are okay.