That's kinda my area.

Nah, not necessary to take the sidewalk along most of that route, unless it can get you off of that bridge. Traffic isn't too fast, and sidewalks are more crowded with yard fences and tree planters anyway. You could probably cut your commute time in half by taking the street, too.

If you take the sidewalk, you have to be exceptionally careful at intersections -- not every car drive can see you even if they're looking for you. Also remember that there are many "intersections" between streets -- driveways, front doors, business entrances, alleyways, etc. You can't go 15 mph a few feet away along a block of storefronts without risking blasting into a customer as they step outside with their dry cleaning, for example.

Go riding some more around the area. If you see another cyclist on the street, go where they go (although don't shadow them too much, lest they think you're following them home ). There are so many of us at every hour on DC streets that drivers are already expecting to see you out there, too.