Hindi ka nag-iisa sa yan, mare! A few of my mum friends din walang spotting even days before labor, kanya-kanyang timing talaga ang katawan, some get it, some don't, so that's totally normal. Pero yung feeling na may nakaturok sa loob at the back pain, plus you're already 39 weeks, I'd really suggest checking with your OB soon lang para ma-assess kung ano na exactly ang nangyayari, better safe na, especially since labor can start anytime at gusto mo na alam mo kung ano ang tunay na labor signs versus false alarm!