Thank you for your question.
As your pregnancy advances the nausea will gradually decrease. Some women continue to have some vomiting through pregnancy. As long as you are able to keep eating and drinking most of the time you need not worry. One way to know this is OK is that the baby is growing well, you are passing good volumes of urine that is light yellow in colour and stools are easy to pass. Generally doctors prescribe safe anti emetics for vomiting in pregnancy. Sometimes the nausea is because of severe acidity which is treated with mucain gel or gellusil three to four times a day.
In early pregnancy its OK to eat what you can and stay hydrated. Once you cross 16-18 weeks your nutritional requirements increase significantly. It will be too much to write on this application so your obstetrician and nutritionist can help recommend the right food and quantities for you and baby's growth.
Common foods to help with nausea are ginger, ice cream and coconut water. However each baby is different and it will express its preferences through your taste for certain foods and aversion to others.
Hope this helps