Eh sayang, macam sulit nak tengok dari description je, tapi kalau you rasa ada line walau pun samar, usually it's a sign! A few of my mum friends pun pernah share test results yang garis-garis samar and they turned out positive, at times tu hormon baru nak build up after breastfeeding lagi. Since you haven't had your period since baby no. 3, better do a repeat test dalam few days or check dengan doctor to confirm properly, sebab sometimes lactational amenorrhea boleh tricky. Let us know how it goes!