Late period, sick at the sight of food in A.M., negative prep test

Lucy • My fiancée and I have known each other since we were 4. We have just moved to JAX from SC abt 1 year ago. So in LOVE!
Omg! What is going on? My period is 3 days LATE, the past two mornings when I see my food, I could vomit! I took a test and the results came back negative. Can prenatal vitamins make you nauseous? I bought a new brand and have only taken them twice and both days, I've felt on the verge of throwing up shortly after. Let me know!