Eh, dua line pun boleh jadi positif even if one is faint, but the fact that the clinic test came back negative is a bit confusing, honestly kena follow up dengan doctor la, either repeat the test or do a blood test (HCG) untuk confirm, sebab sometimes timing or hormon je yang naik-turun macam tu, especially kalau baru je lepas cycle or ada hormone changes lain. A few of my mum friends pernah experience gini, and doctor always recommend tunggu few days then test again or do the blood work je untuk clear picture, better to know untuk sure kan, especially sebelum ambil vaccine.