help please

OK so I have a situation I was in a relationship for six years I tried getting pregnant it didn't work and 300+ pounds my best friend is pregnant with her third child and she has 300+ pounds and funny very difficult to get pregnant I am in a relationship right now and kind of worried that I'm not going to be able to get pregnant I'm focusing on going back on birth control to regulate my systemI tried losing weight and not doing well at it does anyone have any tips or anything I could help