I find this fairly interesting. She may not be all that confident in her diagnosis. It is generally agreed that therapy, healthy diet, and/or exercise are not sufficient to control the symptoms of bipolar disorder. Unlike other mental disorders like depression and anxiety, the scientific evidence strongly shows that bipolar disorder is probably the result of some sort of underlying, specific (though not yet identified) physical pathology.
The other concern is this: in general, when bipolar disorder goes untreated by medication, the more manic episodes will occur. And the more cycles a bipolar person goes through, the worse they tend to get–and the harder they become to control with psychotropic drugs. (It’s called “kindling theory,” if you want to read about it.) Most psychiatrists would tell you that there are significant negatives associated with delaying attempts at pharmocological treatment.
That said–I’m not trying to push you into taking lithium. Some of your symptoms sound manic to me, but I’m also not entirely convinced that’s your problem. (FWIW, I’m a graduate student in clinical psychology.) It just sounds to me like your doctor did not tell you all the risks associated with delaying pharmocological treatment attempts, if you are in fact bipolar.
Also, FWIW, I would seek out a psychiatrist now to discuss these options. A good psychiatrist will not say “take meds now or stop seeing me.” I have worked with more than one psychiatrist who respected my overall reluctance to take psychiatric meds, and my desire to take as few as possible. A (good) psychiatrist will be in the best position to diagnose you, to discuss treatment options with you, and to discuss the risks and benefits of each option.