Eh sayang, first thing, kalau period irregular, kena jumpa doctor cepat-cepat untuk confirm pregnancy dan dating yang betul ya! Important nih sebab doc kena tahu your cycle pattern to calculate accurately. Dari bulan 12 tu boleh jadi reference point, tapi since yours irregular, jangan try kira sendiri, doc punya ultrasound dan blood test lagi accurate. A few of my mum friends yang period irregular pun kena ultrasound awal-awal untuk make sure everything's on track. Go see your gynae soon k, jangan delay!