regular period becomes confusing just in time for ttc

I have had VERY regular cycles for over a year now. Always 30 or 31 days. In August, me and DH decided to start trying for a baby. My period ended up being quite late, which was exciting, until it came. My cycle that month ended up being 34 days, but AF came normally. We tried again this month, and my breasts became sore soon after. I was excited again until I started having some blood on cycle day 26. By the end of the day, I was cramping a lot and it seemed like AF was here. At first I thought maybe implantation bleeding until it became heavy. I used a HPT which was negative, but technically I thought I was testing early since my period wasn't due yet. I might test again on the day my period was due. I don't know why I seem to be early this month after being late last month. The only thing is I started taking thyroid meds almost right after my last period.
I just want a little one!