Hi bb -
I couldn't really say if you are depressed or not; depression is such a personal thing, and the way it effects each person can differ greatly. I will say that some of the symptoms you describe are classic signs of depression, but I think they are also signs of a bunch of other things like bloodsugar imbalance (frequent in dieters), seasonal affective disorder, hormonal imbalance/disorders, and lack of vitamins/minerals (e.g. iron).
I think a talk with your psych sounds like a good idea - heck, he/she may want to run some blood tests to rule out physical causes. I'd make sure to explain what changes you have been making to your diet and activity so that he/she can consider those impacts. Then, it really will be a matter of how severe/how long the symptoms are.
My instinct is that there may be something other than clinical deprssion driving these feelings for you. Whatever you and your doc end up deciding, feel free to come in here for support as you work through these feelings.

Have a beautiful day!