I really need some advice, ttc baby number 1

I've been tracking my periods for a long time. My Cycles are always between 38 and 42 days.

This month on CD 27 I started light spotting. It was dark brown and faded to pink over 3 days. Only enough to show on a panty liner. The day after it finished I started getting pulling cramps (CD 31). Today is CD 34 and my nipples are now really sensitive (but I do get this before AF). I tested this morning with FMU and it was negative. Should I count the spotting as a period and start again? Or should I test again in a few days? I really don't know what my body is doing, I've never had spotting between periods before.

Has anyone had this? All the research I've been doing says I should test positive 4 days after spotting finishes if I'm pregnant but it was clearly negative. :(

Please tell me your experiences xxx