Ah mama, yan ang nakakanerves talaga, ang irregular periods pag may contraceptive, lalo na kung bago pa lang sa iyo yung cycle, kaya totally understandable ang worry mo. A few of us sa mama group namin, nag-injectable din, at may nakakuha rin ng weird spotting or delayed period during the adjustment phase, so hindi ka nag-iisa dito. The thing is, since negative ang PT mo pero delayed pa rin, best na talaga mag-consult ka ng OB para sure, kailangan niya malaman kung normal lang yung cycle mo na nag-adjust sa injection, o may ibang nangyayari. Don't stress too much muna kasi ang injection ay designed to prevent pregnancy, pero the uncertainty is real and only your doctor can give you peace of mind!