Is it too early to start getting fat??

Ana
I am getting soo fat my jeans doesn't fit and I am feeling so uncomfortable with all muy clothes. But I am 4 weeks 5 days!! What's wrong with me? Is it to early to buy maternity jeans? I am not eating that much, I gained 30 kilos with my first pregnancy (thank god I lost them again one year later), could I have something wrong that makes me so fat when pregnant??