Period after miscarriage

I had a miscarriage the beginning of April, I just found I was pregnant and miscarried the next day and I was only 6 weeks along. The end of May I started my period and it lasted the normal 4 days. June came along and I didn't have my period so I waited a week and took a pregnancy test and it was negative. Two weeks later still no period and it was almost the end of July so I took another pregnancy test and it was still negative. What is wrong with my period??