You can always sue, but the real question is do you have sufficient evidence to win? You may. Your own records of what hours you actually worked are admissible in evidence. If any co-workers or former co-workers are willing to provide testimony, that helps. You will need to show that you worked the overtime, and that you were not paid 1.5x your normal rate for those hours. Meal breaks are typically unpaid, if you actually took them, and if you were free to leave the premises and use them as you liked. Since you didn't have meal breaks, those would be included in your hours worked. You were not exempt from overtime, from what I can determine from your facts. It would be worth it to you probably to gather your documents and visit with an attorney, depending upon how long you worked there. You can go back and claim wages for three years, usually.
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I generally agree with Saphronia Young's thoughtful answer. I would only add that my strong suspicion is that you were treated illegally. It's hard to know whether you were working in a position that is exempt from overtime without more facts. Even if you were exempt from overtime, you have to receive breaks. You might go with a report to the Washington Department of Labor & Industries as a starting point.
-Alex J. Higgins