Already hungry all the time and pee twice as much?

Hi, ladies!! I need your advice and help. I am five weeks pregnant as of today, and already all this week I have to eat something just about every hour of the day, and I pee twice as much as I used to. It's really weird! I've also gained about 5-6 pounds, I weigh more than I ever have before. My sister and mom don't understand it either, isn't it too early for this kind of thing? They just think it's because I've always been underweight. Help!!!!