Girls, please advise — I'm 14 weeks and, according to my doctor, I'm n…

Girls, please advise — I'm 14 weeks and, according to my doctor, I'm not gaining much weight. I don't have nausea or vomiting, I eat like crazy but have only gained 1.5 kg. All my tests are fine. My belly is just starting to show; the only thing that worries me is what the doctor said about my weight. Is this normal or should I be concerned about something?