I was barely sick with my first, a son. pregnancy affects everyone differently. articles I've read say that sometimes if you have a stong constitution that handles hormone levels well, estrogen levels can be a big contributor to whether you "get sick". For instance, if you're carrying a boy, you may not experience sickness than if you were carrying a girl where you'd have higher levels of estrogen. Which I know fell right in line when I compare my carrying my son to my daughter. My first was a miscarriage and I did feel sickness. My son none, my daughter...holy cow i felt bad.
I would say listen to you doctor. if you have questions, ask. That's what they are there for. also, only 1 in 4 pregnancies actually go to term. Not trying to scare you, but realize that when they do occur, it's common, not you did something wrong. While drs. can't predict a miscarriage, they are trained to watch for unusual occurances. Ask, ask, ask. no question is silly.
Good luck