Ay, ganyan talaga ang stress at hormonal changes, nakakaaffect talaga sa cycle, lalo na kung may major changes in your life recently na nangyari. I'd really suggest going to your OB-GYN para malaman niyo kung ano talaga ang dahilan, kasi three months is quite a long gap at gusto ninyong ma-rule out kung may underlying issue na kailangan i-address, plus mas confident kayo kung may professional check-up na.