If they say you are covered until the end of the year, I would think you are covered to the end of the year. I would communicate with them though, I think there is a provision for you getting your own plan from them, a "continuation" since you are no longer in school, etc.; I believe the change in circumstances makes your situation different so you can get insurance "now" rather than having to wait until the next open period/year. Don't know though, ask the insurance company.

http://www.dol.gov/ebsa/faqs/faq-dependentcoverage.html