when do I start showing?

I'm 5'4" and 118lb. I'm only almost 6 weeks along, yet I'm already gaining weight. I'm too exhausted to exercise as vigorously, and many eating habits have changed as well (not as healthy lol). Should I be gaining weight from the pregnancy this early or is it because I'm eating bad and not exercising? I think I'm looking for excuses to eat more and be lazy and indulge in comfort food....