I worked with and was friendly with a woman at one of the companies I worked at years ago and she had quite a list of reasons, similar to your own for wanting her tubes tied in her early 20's. I remember she said that her doctor told her that only after a certain age would they consider it. I'm trying to remember the magic number, 26 comes to mind but it I could be off by a year or two. Has to do with liability on their end. Doesn't hurt to ask and get the facts.