[Harmony♥]

If you were pregnant, your body wouldn't even know it yet. So, the weight gain and missed period are probably due to other factors, like stress and your recent change in diet. Nobody can tell you whether or not you're pregnant, and at this point, a pregnancy test couldn't even tell you because it couldn't give you an accurate reading. Wait another week (or two weeks from the time you actually have sex), and take a pregnancy test then.