If it's really nagging at you and you can afford the tests easily (they can be quite expensive, especially if you are peeing on a stick addict), I don't think it would hurt to test now. Wait until morning though so you have super concentrated urine (most likely to get a positive result IF you are pregnant, testing so early). If it comes up negative, then I'd wait until after your missed period. It all depends on how patient you are to see a positive. Just remember that a negative this early could turn into a positive until you have your period.
Rae (27), DH (26), Lucas (6/3/12), #2 due in December