Getting ready for preschool

Jack is finally potty trained at the age of 44 months. That is exactly 3 yrs 8 months old if you are too tired to figure it out. :) Well, now we can send him to preschool.
I just think I am not really ready to put his life in someone else's hands at the moment. Those people don't know my son like I do. They don't know that when he itches his chin, he is going to start coughing from his asthma and he needs a treatment sooner rather than later.
As I sit here thinking of it, I am not sure if I can prepare my son for the world, ever. It is a very emotional experience that is hard for moms of non food allergic children to appreciate. I feel anxiety about letting him go without me there. I feel extremely overprotective. I am the type of mom that lets my child experience things by letting nature take its course. I tell my child not to put their fingers in the door or they will get hurt. My son has chosen not to listen on a few occasions and gotten his fingers pinched. He listens now when I tell him that. I never viewed myself as overprotective. I dont think I feel comfortable being that. I view overprotective people as "Nervous Nellies" that just freak themselves out over the smallest things. I like to be calm and rational. But I don't feel calm and rational.
I know that we will overcome this hurdle in our life and many more in the future, but I didn't bargain for the incredible stress that comes with it. I try to keep things in perspective and remember the funny things about food allergies. Like when I was reading Jack a book called Allie the allergic elephant. Allie's mom carries her epinepherine kit and Jack asked me where was his epinephrine kit(last summer he did this!) Or when he pretends, he gives me ice cream and peanuts all the time for snacks. I just hope he stays as happy and positive as he is today. I thank God that we are healthy and alive.