Use this link to use the PSU calculator. That's the only sure fire way to know. I'd say you're definitely close to pushing the limits on the 550, but the calculator will say for sure.
Also, you don't want to purchase a PSU that gives you no room to add/upgrade in the future or you'll find yourself having to buy another PSU. It's best to just go ahead and pay a few dollars more now vs. paying a LOT more in the future.