I can understand her feelings and its not that uncommon. Do try and suggest that she check out the sites I mentioned. If nothing else it will let her know that she is not the only one out there with this problem. And the sites are kind of fun to navigate.
She is the type that won't look for a way to help herself. Everyone has to do for her and if she don't get what she wants to blows up. Says she has no family and that her friends are the only ones there for her.
Taking meds has only been one half (or less) of the answer to dealing with ADHD. To deal with it, you have to understand what it is doing to you so you can learn compensating behavior. The best thing that your sister can do is to make sure that she really understands how it effects her. Then she can start learning how to deal with it. Yes, meds can be helpful if you have a job and need to concentrate, but they are not always essential for daily life.
There are a couple of adult web sited devoted to AD/HD. They are run by people with AD/HD and can be very helpful. She might want to check out
- http://jeffsaddmind.com/ and http://totallyadd.com/.