I'm late!!

Mikayla
I had a Babygirl on 5-27-15, my first period was on July 3rd-6th, July 30th-August 1st, August 18th-21st.
I was told on My Cylce App that I'm 5days late... On Glow I'm only 3 days late.
I took a cheap family dollar brand test that was a blue dye and it said BFN on September 12th. 
Do you think I'm just still irregular or the test was faulty?? 
Pic for attention