I'm sorry you're facing such a difficult situation.
For more info on bipolar disorder in children, I suggest checking out:
nami.org and nimh.gov (that may be org, not sure). This might help in providing you some additional answers. Above all, I would get a second opinion if your son does receive a diagnosis of bipolar disorder. Every pyschiatrist has a different set of criteria by which they personally make a diagnosis. BP disorder is often confused with ADHD and those illnesses are treated very differently. I would also think about finding a children's therapist who is accustomed to working with kids with this diagnosis.
BP disorder runs in my family (myself included) and I understand your fear of starting your DS on medications should he be diagnosed. My DS has about a 50% chance that he inherited BP from me, and the thought of him taking the kinds of meds I do is scary. My personal feeling about meds is that they are a necessary evil in treating an illness like BP. The damage and chaos brought about by the symptoms are far worse than taking meds. This is my opinion only, other people feel very different on this subject.
Best to you, please post again with an update or PM me.
Lauren