Need help with cycling

[Solarris]

I am currently trying to cycle my first tank, a 55 gal. The ammonia is at 1.0, my nitrites are at 0.1 and nitrates are 2.5 and the temp is 75. They have remained at these levels for the past 3 days. I started with 5 goldfish (my lfs told me that was plenty) and have since lost 2 and have 2 more that I think might not make it with 1 that is looking as healthy as ever. Is that enough fish or should I add more goldfish? I've read articles that said 2 or 3 fish is enough but i've also seen one that says you need 2 - 3 per gallon. Also, this tank has been running for about 3 weeks now and I was wondering if those numbers are about where it should be? I stopped by the lfs this morning and asked these questions but the girl there just suggested a water change, which didn't sound right to me, before admitting that she didn't know anything about cycling.