a couple thing of the top of my head that you could ask yourself/explore on your own:
do you have a hard time doing things for yourself that aren't related to money? (in other words do you have difficulty in taking care of yourself in general?)
are there any times when you do buy something and *don't* feel guilty or bad about it, and if so, looking back, was there a difference in feeling at the time in terms of your purchasing decision, (and what was the difference)?
do you ever buy something, feel bad about it, but looking back on it realize it was a good purchase and you used it as much as you thought you would?
are you perfectionistic in other areas of your life?
i'm not sure if you were looking for advice on "what do do" in terms of contacting professional help, finding a support group, etc.; it can help sometimes to try to make sense of these things on your own.