New Year's blues

Because who can be sad when there's a Happy Turtle in the
hiz-ouse?

Not sure if I'm feeling blue because the holidays are over and it's a bit of a letdown (recall, I spent the first week of December in a kind of funk because NaNo was over), or if it's SAD, which I also usually suffer from.  Or if it's something else entirely.
You know, I think it's a bit of all three.  I know it's sad that the Christmas decorations have to come down soon.  I also think that the near-constant cloud cover and frequent snows we've been getting have something to do with it. 
My main concern is the "other" category.  Part of it is irritation that I work seven days a week- at a job I love, with clients I enjoy, but still, seven days a week is seven days a week- and another part is a kind of depression that comes from being a fifth wheel because every time I get together with my family, everybody else is paired up and I find that incredibly irritating.
Sue me.
Part of it is also that I don't feel like I'm doing anything.  I have these great ideas and every time I jot them down, I've got this little voice in my head saying, "it's been done before" or "no good".
Mom made a good point, I suppose.  If I'm wanting to be an author, I can't be so sensitive.  The thing is...I don't think any of these things is the real problem.
I think I'm just in another of those funks I get into every year around this time, when I just don't see the point.  Of any of it.
Don't look at me like that. 
Tomorrow will be better.
Especially if this headache goes away by then.