Wow, I'm so glad I stumbled across this thread. Not only have I not read the Spoon Theory before and found it interesting, it's very thought provoking.
I also have invisible disabilities, nothing life threatening or needing of surgery, but so many little things. The main one however is the fact I have depression, officially diagnosed at 14 as Dysthymia. Unfortunately Dysthymia is classified as the less extreme of depression diagnosis and even people with depression often misunderstand it. Even though people with Dysthymia do not often have the radical mood changes, your mood is still low. It is rare to experience a 'high' or any great amount of happiness. Every day is a low for example and rarely have a sense of hope.
Beyond that, I've also been diagnosed with scoliosis, genu vulga and recurring tendonitis of both wrists, and I've been told the doctor thinks my random and serious ice pick headaches are due to a pinched nerve in my neck. There's a possibility of more, but unfortunately my doctor isn't one who listens and just tries to cure the symptoms rather then find the cause.
Leading to of course problems with weight, exercise and being able to do a lot of things, and definitely problems in relationships as most everyone I've been with doesn't understand this.
Even my husband of 7 years doesn't understand it, even tho he is fairly supportive, but I know that sometimes he's still resentful that I can't help out with chores most days. Nor does he understand the despair that comes with wanting to be useful and able to work but being unable to because you can't deal with people constantly.
So I'm very glad that this thread is here, it's rather relieving to know of others with similar problems due to disabilities.
Part of what's made me smile reading a lot of this is seeing how people here are not overly bitter, and say that they'd rather not have anyone else be able to understand... as nice as it is to have others do. It shows a wonderful strength, and reaffirms my personal beliefs.