AF is late. Negative test

Ashlie
Hi ladies so my period is late. I would normally have an average cycle when I get my periods but cause I only had the implanon out early last month I don't know what to expect. 
Maybe it's too early to test? Cause i tested this morning and it was negative. 
I am not entirely sure when I ovulated. 
But Iv been having lower back pain and slight twinges on either side of my abdomen since being late. 
I'm really nervous as me and my partner are really wanting a baby. TTC baby #2.