Not sure what is happening

On Christmas <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> 2018 I had a miscarriage. I was not very far along but it was exciting. It’s been longer then a month and my cycle is normally only 26 day my period is now 7 days late. I feel different not my self eg. tired, constipated (always have regular and normal toilet stops) ,keep having slight cramps (I never get cramps before or during my period) I have been taking pregnancy tests since the day I missed my period and they have all been negative. Is this what your body does after a miscarriage? or is there something going on with my body I have a doctors appointment in a few days do I keep testing?