It's really hard to go from a good work environment to one that is less than desirable. I really feel for you! I think it's reasonable for you to be offended by what your boss said about the uniform. As a manager, she does have the responsibility to make sure her employees meet standards, but there were certainly many more tactful ways she could have handled it if she felt you weren't dressed according to company policy. Did they give you an employee handbook when you were hired? If so, it may contain information on this and also about how to handle a grievance if you feel she's not treating you correctly.

If there are other employers hiring for your type of work, you can always check around and see if you can find a better position. It used to be bad to switch jobs a lot but today it is quite common, especially if you can find one that pays better or has better benefits. This makes it easy when you go on an interview and they ask you the question, "Why are you looking for a different job?" ADVANCEMENT, OF COURSE!