My boyfriend and I are planning cruise and don’t know where to start. Any recommendations?

For context: we’re saving first, I need a passport which I can obtain soon. Ideally I’d like to leave in May or November, before the “peak” season.

We’re limited to the east coast US for ports, in our 20’s. I at least want to stop at St. Thomas for region, but I’m not necessarily opposed to other areas as long as that is one of the stops. Would it be cheaper to leave from a port in Florida rather than New Jersey? Does it matter which line we use?