Congrats, mama! Ang positive PT with two clear lines is definitely reliable na, lalo na if consistent siya sa three tests mo, that's a strong sign na you're pregnant talaga, kahit konti lang ang delay mo from your expected period! A few of us moms here had the same experience na positive na agad even with just a few days delay, kaya don't worry, it happens, especially kung super regular ka talaga before. Best thing now is mag-schedule ka na with your OB para ma-confirm with blood work or ultrasound, and makuha na rin ang official due date mo, mas accurate kasi ang dating based sa first ultrasound rather than counting lang. Excited for you, mama!