Irregular periods

Erica
I was on depo provara for about 2 years or so. I've been off it for about 6 months now and trying to have a regular period. When I was on the birth control I had no period at all. I've been keeping track of my periods and when I have intercourse. My <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period tracker</a> says I missed my period last Sunday. I took a pregnancy test and it was negative, could it be wrong? We are trying to conceive together but don't know how really. This is our first time trying for a baby. Any advice or anything to help me..