More than likely, yes you would be. Have you have any bleeding or spotting? And was the test you took that was negative done at a different time or a different brand? IE you took a test at night rather than in the morning?
if you havnt had your period in 3 months, i think its time to see a doctor.
I agree that you could be pregnant. When was the last time you tested? It's best you see your dr at this point since you haven't had a period in so long.