Trouble gaining weight

I have always had trouble gaining weight my entire life. I have. Always been really Slim also being 6 foot tall. I am very athletic and I model it's always been the norm for me. i keep seeing all these beautiful mothers posting there bumps around the same time as me being 11 weeks pregnant my first pregnancy. I still haven't gained a pound and still look extremely Slim. have been receiving hate comments/messages it's very discouraging and makes me worry more then I already am. All I want is a healthy baby I eat and eat and eat so much food my body type just doesn't allow me to gain like some people. I don't think it's fair to say it's rude to make fun of somebody for being overweight but yet make fun and Bully those who are slim and can't help it. I just want to feel beautiful during my pregnancy like any other mother.