Metformin symptoms or pregnant

Danielle
I started taking metformin on Jan. 4th 500mg for 5 days then 1000mg for a week now I'm up to 1500mg. My average cycle is 35 days. I took my first pregnancy test a week ago big fat negative. 
I feel as if im having pregnancy symptoms waking up in the middle of the night sick, just not feeling right nauseous in the mornings. Is this a usual side effect? Or should I take another test?