My DD has ADHD. She never had any febrile convulsions. Therefore your theory is disproved.
Oh wait, that’s not how science works. It relies on provable facts, not wild ideas.
DH, DD and I are all fully vaccinated according to whatever was the standard childhood vaccination schedule at the time of our childhoods. Two out of the three of us have ASD and ADHD. Surely it should be all three if vaccines cause autism/ADHD?
DD exhibited ADHD behaviours while in utero. She exhibited ASD behaviours prior to MMR vaccination. She was autistic and ADHD from the moment she was conceived. In fact we knew before we conceived her that there was a higher than average chance of her having ASD. How could we know this? Easy - genetics. DH has ASD and ADHD meaning that any children of his have a higher chance of having them too.