Late!

I have two different period tracker apps. One says I'm 4 days late, and eve says I'm 2 days late, so I'm just gonna go with 3 days late in the middle. I am sexually active with my husband, and I quit birth control for health reasons in September. All last week I was nauseous, diarrhea, lower back pain and fever. This week I'm constipated, fever, still back pain, heightened sensitivity to smell and no appetite. I took 2 pregnancy tests two days ago, both negative. Could it be too soon for anything to show? Or any advice? I just feel pregnant if that makes sense. And I do not feel well at all. I am again late, but also have a white milky discharge.