Two things come to mind here -
1) It's been discussed before here, that Maladaptive Daydreaming Disorder seems quite common among autistics. I used to do it a lot myself - escaping into a fantasy world inside my head, that was so much better than the real world!
2) Your daydream seems to be the yearning of a person with an invisible disability that no one cares about... So in your daydream, you have an obvious physical problem, and people do care. In that way, it makes perfect sense to me!
If it comforts you to escape into this daydream now and then, and it isn't interfering with your real life activities, I don't see a problem with it 