Whirfloc and other fining agents such as Irish Moss are usually added in the last 10 minutes of the boil process, not while steeping the grains.
Even if you got the beer into the fermenter before realizing that you failed to add the whirfloc wouldn't hurt your beer. It's not a necessary ingredient. All it does is help clear the beer up and reduce chill haze. Neither one of which can be tasted.
Relax and have fun. YOU'RE MAKING BEER!!!!