It's hard to say how to smooth your hull without a better description or a picture.  Telling us what you've tried so far might help, too.  If you just have small blobs of epoxy across the surface, on the order of a pencil eraser in diameter to a dime size and not too thick, cut them down with a carbide scraper.  Lots of posts here and on the web about scrapers.  Follow up with a random orbital sander attached to a vacuum to about 180-220 grit.  If you have wavy curves where the glass has floated or the bottom ply isn't fair, you'll probably need to use a lightweight filler to get your hull's bottom fair.  The more epoxy (NOT GLASS CLOTH) you sand off, the less weight you'll carry around when racing.  Let us know how you are doing.

First: It takes a lot more sanding (and sandpaper) than the instructions would lead you to think in order to get a smooth surface. And if this is your first build, you most surely used a lot more epoxy than you needed.

Second: You don't need a finish that looks like a production model to have a boat that performs well. My favorite kayak has a notable kink in the bottom but is a delight to paddle in all conditions.

-Wes