Aww sis, yan talaga ang nerve-wracking, been there with a few of my mum friends and sobrang stressful ng waiting! Nine days delay with negative PT could be maraming reasons, stress, hormonal changes, irregular cycle lang, or baka mabilis lang mag-ovulate that month, kaya best talaga is to see your OB para ma-check properly, either through blood test or ultrasound para sure na. Don't stress yourself too much muna habang naghihintay ng appointment, pero definitely go pa rin ha, para mapakita ng doctor kung ano ang nangyayari. Sending you lots of love, most of the time, everything's fine!