Lepas 4 hari lewat period memang stress kan, tapi UPT negative bukan bermakna tak pregnant lagi, sometimes hormones take longer to show up, especially kalau cycle tu irregular. A few of my mum friends had the same thing, and few of them actually dapat positive result on day 7 or 8 lewat period because hCG levels still building up. Tapi honestly lepas UPT negative 2 kali, I'd suggest go see your gynae to rule out other reasons period lewat, bisa stress, hormonal imbalance, atau pasal lain je. Jangan tension sangat in the meantime, easier said than done I know, but stress dapat delay period lagi.