I'm sorry that you're dealing with all of that :(. Have you discussed a possible diagnosis of hypermesis with your doctor? I'm not sure what else they could do other than the zofran or other medications like it, but sometimes certain meds work differently for certain people. Maybe there is one that your doctor can try that you haven't had yet.
Are you taking prenatal vitamins? If so, talk to your doctor about possibly changing those over to Flinstones vitamines instead. Sometimes the extra iron in the prenatals can really bug our stomachs and that can wreak havoc when we're already dealing with morning sickness in some form. My doctor put me on two flinstones a day and told me to take vitamin b-6 a few times a day (if you're going to do the b-6 talk to your doc about how much to take) and it didn't eliminate it, but it did help a bit. That regimen in addition to your prescription meds might help if your doctor approves it.
Another thing you can talk to your doctor about is Unisom. Some doctors recommend it to pregnant women to help with morning sickness. How it works, I couldn't tell you. I go to forums on Justmommies.com and several women were told to take a certain amount and they said helped.
Another important thing to remember is that you're more likely to get sick on an empty stomach. Don't worry about what you're eating so much as that you are getting some kind of food in your body. If it sounds good, try it. I survived on McDonalds, pizza and Subway subs for the first 13 weeks of my pregnancy. For some reason that was more appealing and could minimize the nausea more than crackers or anything else. Don't forget to drink too. When we throw up a lot we get dehydrated quickly! If water bothers your stomach (it did bother mine so its possible!) look at trying lemonade, peppermint tea, ginger teas, ginger ale, plain soda water, sprite, 7up, flat coca cola (some women say flat ginger ale at room temp is easier as well).
I've heard that the sea bands that help with motion sickness can sometimes help take the edge off of morning sickness.
Good luck, I hope you can find something that helps you!