Nausea Medication

My doctor had originally prescribed me Diclegis for my severe morning sickness, I had been taking samples of it that she had given me during our initial appointment. But when I went to fill the rx my insurance wouldn't cover it without a prior approval first. So instead of my Dr sending an approval they just wrote an rx for a different medicine which was covered, Ondansetron (generic for Zofran). I've only taken them a few times, once every 2-3 days. But I've been reading many articles about how there are possible birth defects from taking this drug early in the first trimester, and I'm currently only 8w1d. The fact that Diclegis is approved by the FDA for pregnancy where as the Zofran is not makes me very nervous. I know zofran has been prescribed for morning sickness for many years but there isn't enough evidence to neither prove or disprove birth defects. Anyone else taking this medicine have any opinions on it? Am I being super paranoid for no reason?