Being left "wing"

I was listening to NPR this afternoon (Talk of the Nation), and there was a rather brief discussion of what constitutes the "base" of the political parties.  I'm quite interesting in this, because it's something I've thought about a lot over the last few years.

I've always been part of the Democratic "base" because I consider myself a Democrat, and  I vote in primaries, and I always vote Democratic in general elections.  Also because I'm a committed ("kneejerk"?) liberal, and I support "liberal" positions, like a woman's right to choose, immigration reform, and gay "rights" (this is, equal rights for everyone). 

But I've always found it odd to be considered the "left wing" of the party, and therefore the mirror of activists on the right.  Because my positions are very mainstream and are held by the majority of Americans.  Meanwhile, the "right wing" of the Republican party are the people who insist Obama is a Muslim, and think the government is trying to destroy their lives, and indulge in all sorts of conspiracy theories.  In other words, much more marginal positions.

And what is the difference between me, a committed Democrat and supposed "far left" representative of that party, and "moderates" or independents?  They don't affiliate with a party, but we share the same values - I consistently hear their political positions described as coinciding with my own, both in terms of social issues like abortion, and in terms of our perception of the appropriate role of government (e.g., regulating industry and providing a safety net). 

At least that's how it seems to me.  Maybe my perception is skewed, but it does always strike me when I hear some comment about the left wing or the far left or something along that line, because I just don't see myself and my political contemporaries in that way, and it's hard to imagine other people seeing us that way.