Laura, I'm glad to know that you have found meds which work for you. As I have written, for those who do have chemical imbalances, medications can be helpful, but as you said, it usually takes trying many different meds, and even combinations of meds, to find what works for a particular individual.
With your many years of experience with depression, I'm sure you know that psychiatric illness is not an exact science. There are many chemicals/hormones which are involved and can be unbalanced. Also, different people respond differently to medications, largely because the doctors do not know exactly which chemicals may be causing the symptoms. It can be a very frustrating journey, and many people give up on meds before finding the right ones, which seems to be your point--to not give up.
In my article entitled "Depression and Childhood Abuse," I wrote about the fact that painful life events can actually alter brain chemistry, sometimes predisposing sufferers to depression for years. However, not everyone who is going through a hard time has a chemical imbalance. They can't check your blood or do an x-ray to see what's going on. They can't take a sample and see a particular "bacteria" that is causing a disease, knowing it will respond to certain "antibiotics."
As you said, Laura, depression is treatable, but there is no magic pill. In most cases, even when a med is found which is effective for a patient, its efficacy plateaus after a while, and then begins to lose its efficacy. Talk therapy, or psychotherapy, have been found to be as effective as antidepressants in long-term treatment for depression.
However, each patient is different. What might work for one might not work for another. I agree that it is important for sufferers of depression to seek treatment, including meds. I don't, however, believe that the labels we put on psychiatric illnesses are so important. Each patient experiences the symptoms of his or her disease at differing levels, and different doctors might put different labels on the same person. What matters is that we get the help to make us feel better, and I know that we are all happy that you were able to do this.