Oh, thats right. I'm using a reverse nginx proxy to the nodejs server for speed and security reasons, so everyone's IP is logged as 127.0.0.1 (localhost)
That explains the lack of unique visitors

You need to specify a custom log format to log the X-Forwarded-For header.
app.use(express.logger(':req[X-Forwarded-For] - - [:date] ":method :url HTTP/:http-version" :status :res[content-length] ":referrer" ":user-agent"'));