Found out pregnant at 3 weeks

I just found out I was pregnant on Sunday. This is my second child and he's 1 year and 1 month. I was 3 weeks so I am almost 4 weeks. Is it normal to feel nauseous and like I'm starving already this early? It's not super nauseous like ny first pregnancy but also it's way earlier that my first. I start getting nauseous and sick around 7 weeks. Also I've been losing weight which I was losing since first baby and here recently since i cut Cokes out of my diet. Will I be ok if I continue to lose weight? I am currently 287. Was 280 when I first got pregnant with first child and my first appointment is December 22.