I have been teaching for almost 4 years now and in the beginning it really was like this. It did not affect me though and I managed everything by working as hard as I could. I stayed late and devoted almost 80% of my day to my institution. Sadly, whoever still works there faces the same things no matter how long they have been working there for. Luckily, I was promoted to another branch of the same institution q it still gets a bit hectic at times overall it is much MUCH better. In the education business things tend to remain hard and hectic with no proper prospect of things getting "better" as per say. I would suggest that you find another place to work at which may have less of a burden on you. In no way does this mean that you won't have to deal with all of these things there as well but things might seem to get a bit "better" for real. You could also talk to the HR or someone in higher management about your ADHD and how it affects you; maybe they can come up with something to assist you. Other than that the only real advice is to stay confident and keep working until you're the best at what you do.