Advice needed! Spotting!

Hello, Netmums!

Well, I'm quite new to all these things..
So we are trying for a baby, aaaaand I'm bit lost here now 
My period is due in 11 days.
And now i'm 4-5 days post ovulation. Past 3 days I'm experiencing HORRIBLE lower back pains  , migraine and I'm obsessed with Tea with milk..  My mood is changing like London's weather every 5 minutes .
Pregnancy test - BFN.
Yesterday I noticed light spotting (Pinkish) after we had "funny time" with my husband. That is what got me worried. Today I'm still spotting but it got bit Brownish. 
I made Pregnancy test today again - BFN. 
Girls, can it be a pregnancy, or it's just me feeling unwell? 
I'm scared to raise my hopes up!

Thanks for your advice,
Saule