I had terrible nausea and vomitting from 7 weeks until around 22 weeks. I tried lots of different things, the only thing that helped was the travel sickness wrist bands, my gp recommened them. They did improve the nausea and reduced my sickness.
I was exactly the same. Had no vomitting apart from the odd occasion. Then I'd have some nausea through the day, but it hit worse at night and it kept me awake. I had crackers, ginger biscuits and rich teas recommended, but they actually made it worse. The only thing that helped at all was sipping water and wearing travel bands which I would squeeze when I felt really rough.
I think it is a bit of trial and error really. Something that helps one person doesn't work for another.