still haven't had a period

So I was supposed to start on the 12th but I still haven't I did about 10 different tests last week and the week before and they were all negative. I decided to wait until the 12th of August to try and test again. but now I'm spotting. I've have all kinds of symptom tender breasts, nausea, mood swings, etc. every one is saying it just might be stress ( which it might my husband was just diagnosed with stage IV melanoma) but I cant help but worry since I've already has one miscarriage in November of last year. like what if I'm pregnant and losing it again?