Since you are 21, the pharmacist violated HIPAA when disclosure was made to your mother. You might review this website for more information: http://www.hhs.gov/ocr/privacy/
here is no simple way to answer your question about the most you could expect financially. But, I would encourage you to file a complaint with the pharmacy as well as the WA board of pharmacy at http://www.doh.wa.gov/Pharmacy/
Consultation with a local attorney on this would be your next step as there are time deadlines to filing such lawsuits. The amount of compensation available will depend on the laws in WA regarding personal injury damages and how such cases have been resolved historically by settlement or jury verdict.
Good luck to you and your family.
While I do not practice in your state, if you are under the age of 18, your parent has the right to all of your medical information. You can expect to obtain $0. It was also not negligence for them to disclose the information, but vital to your health. If you attempt to file suit, I would expect you would likely be required to pay the pharmacy for its attorneys fees.