Nausea

We are pregnant with twins after our first round of IVF after 10 years of trying. I am sooooo thankful to be pregnant, but I have had really bad morning sickness. I am currently 9 weeks. I throw up every meal, every snack and dry heave when my stomach is empty. I am so afraid to eat. I broke down today and cried and cried. The doctor prescribed me Zofran and it has helped tremendously, but I feel so guilty for taking it. From what I have read and researched, zofran is perfectly ok to take even in the first trimester except for years ago several women filed a lawsuit saying it caused birth defects in their babies, but no evidence backed their claim. I had tried several different natural remedies, which didn't work, resulting to this last resort I feel. What are your thoughts or experience with Zofran?