Sayang, I understand you're worried, tapi please don't panic dulu okay. 7 weeks tu memang sometimes gestational sac boleh tak nampak lagi, especially kalau dates nya uncertain (which is common with PCOS and irregular periods macam you punya situation). The brownish discharge pun bukan selalu sign of problem. Since your doctor dah ask you to come back for repeat scan in 2-3 weeks, that's actually the right move, they're giving baby time to grow so it'll be clearer. I know the waiting is agony, but try to rest and not google everything (habis anxiety je!). A few of my mum friends had the same experience, and everything turned out okay. If you get heavy bleeding or severe pain before your appointment, go to the hospital straightaway, but otherwise, trust your doc's plan ya. Hang in there!