Aiyaa, don't worry lah, sometimes hormonal pills ambil masa nak settle dalam body, especially kalau first time you're on it! Tapi period yang tak datang during the break week tu memang perlu check dengan doctor, sebab bisa jadi side effect dari Yasmin atau ada benda lain, better be safe kan. One of my mum friends sama jugak situation dia masa awal-awal, and her gynae said badan dia still adjusting. Just make an appointment with your doctor lah to make sure everything okay, boleh juga they adjust your dosage atau recommend something else yang lebih suitable untuk you.