That's really sweet. I have friends who try very hard but fail (dairy free cake sandwiched with real cream!) and others who always have something in for my DD, just in case. I love that they all try though.
Not many words of wisdom I'm afraid but empathy. My DS has developed the lip swelling and facial hives this year to an unknown allergen. We are waiting for an appointment to go back re epipens after a severe reaction a few weeks ago.(breathing difficulties and freezing cold feeling as well)
I have felt the same re letting him out, going abroad etc. I rationalized it to myself that life is a risk - even crossing a road but simple risk assessment and care limits that risk. I stopped DS going out to play with his friends for a while as I worried but hated seeing his little face peering out of the window longingly so made him play right outside where I can see him and only to go up the road when neighbours boys who are 11 and 13 are with him.
It is a burden and I hope you have a fabulous and relaxing time abroad. And from reading all your posts (esp the epipen and floor one!) your DS sounds like a normal, inquisitive, adventurous little 4yo and you've done that despite your fears so should be proud.