Hello, my name is Dr. Farwell. I can try to help answer your question about Milo.
Is she eating/drinking normally? any vomiting or diarrhea that we know of (probably hard to tell with as much time as she is wanting outdoors)
Does she appear to be loosing weight or weak in any way?
Unfortunately many kitties decide they love the outdoors and want to spend the majority of their time there. If she is eating/drinking, and not losing weight, and appears outwardly healthy ..... likelihood is that she simply loves the outdoors. Is she spayed?
If any other symptoms develop such as the things I listed above, I would definitely recommend an exam and some blood screening tests.
Please feel free to respond and we can discuss things further.