Simple answer yes, if your asthma will affect your ability to do your job. Your asthma is not controlled as well as I would personally like, you've had 2 hospital stays, and the blue lips over the weekend, where you were luck, you should have gone in, you can't afford to pish around and ignore something like that, at best it would have been a precautionary check, at worst a bed of stainless steel.
I know you know better, as a trained first aider, and from some of the advise I see you post, you should be taking better care of yourself. For that vast majority of people asthma is controllable, you I suspect are one of those, you just need to learn the signs and adjust your medication. Unfortunately this site has more than it fair share of the population with difficult to control types, and can give you a worrying distorted picture.
Visit the site I emailed you, check out some the info and if you can get things under control and show that you can manage your asthma so that it won't compromise your ability to do your job, and above all the care of the children you're responsible for, you owe it to yourself as much as the children. How would you feel if you had an attack, and a child required medical attention.
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