period tapi positive

hi semua ade x yg pnh jd....selalu period tiap2 bulan 15 hri bulan.. bulan 12 sy period 30 hri bulan . lepas abis period bulan 12 tu dlm 3 hari mcm tu test hcg double line tp samar2.. bulan 1 x period bila test hcg double line terang sgt. kalau mcm tu nk kira dah brapa weeks ye. belum scan lg. tu yg nk try kira sendiri