Hi mama! Spotting usually has actual blood (kahit kaunti lang) mixed in, pero kung ang discharge mo ay more on the brownish/yellowish side without active bleeding, it's likely just normal pregnancy discharge, especially since wala kang cramping at lab results mo normal na! Pero honestly, since you've had spotting before at may malalim na history ka na with the utrogestan, best approach pa rin is i-mention sa OB mo during next visit or kahit magring na lang, para mapakita mo exactly kung ano ang discharge at ma-ease your mind completely, no harm in asking, lalo na since 16 weeks ka na at gusto mong sigurado lang. One of my mum friends had similar history at nag-relax sya lang talaga after OB confirmed it was just normal discharge, so hopefully same thing para sayo!