5 days late, Backache and BFN

Hi, my period was meant to start on the 7th and is normally just on time or a day late. It is now the 13th and still nothing. For just over a week now I have had back ache and a light flow white slightly sticky CM.

I took a test on the 7th and one just now and nothing. Losing hope very fast. Is it it just too early? When should I test again?

What do you guys think? 😢