Week 12 and I have gained 5kg

I'm in Week 12, and I have gone from 54 to 59kg. I eat very often since I am pregnant to avoid nausea. I'll start vomitting whenever I feel hungry (even the slightest), and I cant let it as I need to teach in class. Lesson hour usually varies from 2 to 4 hours, sometimes back to back. Too small a portion can't last long before I'll feel nauseous again. Any advice/tips? #advicepls #firsttimemom #pleasehelp #nausea #morningsickness