Too much Zofran?

Hello everybody!

I’m currently 6 weeks and 2 days and experiencing debilitating nausea and vomiting. I can’t keep anything down and I’m dry heaving more than anything. My doctor told me to take 8mg of zofran 3x daily, but even that doesn’t do the trick every day. Is there a limit to how much zofran can be taken to minimize nausea and vomiting?