It might be helpful to keep a mood journal. That way you can look for patterns over time. It might help you distinguish hypomanic behavior from a healthy and happy mood.

I also agree with Sarah. Our bodies are like a chemistry set and proper balance is critical to maintaining your baseline mood when you have bipolar disorder. Adding alcohol in the mix is like adding another unexpected chemical to an experiment. You can never be sure how it will react and you oftentimes won't get what you hoped for.