I need help I weigh 210 and my BMI is 39

Is that a reason why I can not get pregnant I have been trying for 2 1/2 years and I'm only 20 ? Nothing works my doctor told me a while back when I had my child when I was younger that I would need to loose weight to have another baby ? But I know people that weight more and have babies like nothing :( is there something wrong with me or should I just take the doctors advice ?