Advice- imantation?

To start with AF was due Thursday, November 27.  On the Saturday before, which was 5 days before AF was due, I started noticing some brown discharge when I wiped. This grew a little stronger but it was still just spotting. On Monday it had some red to it but still mostly brown and I only had to use a panty liner. This ended on Tuesday. Along with this I have noticed some heart burn for the last couple of weeks and I never get heart burn. I have had maybe two instances since ovulation in which I felt nauseous, but nothing further. I also noticed some breast tenderness but this could just be AF symptoms. I am never early with my period but occasionally I am late. Today is Saturday and since AF was due on Thursday but I had that brown spotting a week ago, I guess I am just unsure if I was early or if I am late and I experienced implantation. I did miscarry in May, but it has been long enough to try again. Any one else going through this. I have not tested because I am afraid it will be negative.