Uy, mama, this really needs a doctor's check ASAP, kahit delayed period lang with negative PT, the brown discharge and symptoms kailangan i-confirm ng professional, hindi lang guess work. Could be maraming things, and you deserve proper clarity, hindi worry lang.
A few of us moms have been through delayed periods na confusing, kaya alam ko how stressful it is, but honestly, best move is call your OB or go to the clinic para may proper exam at maybe blood test if needed. Don't stress yourself guessing, okay? Doctors are used to this, walang awkward. Keep us posted once you know na, rooting for you!