Aih, this must be so stressful lah, those faint lines are the worst because you don't know whether to get excited or not! Honestly, from what you've shared, your doctor nampak memang cautious jugak by asking you to come back on 13/12 to scan again instead of jumping to conclusions, sometimes pregnancy lines do take time to develop, and sometimes it's a false positive, so waiting for confirmation makes sense. A few of my mum friends went through similar situation and one of them turned out to be pregnant (but HCG level just slow to rise), while another did have PCOS, so both are possible at this stage, unfortunately. I think the best thing is to just follow your doctor's timeline and keep taking the folic acid (at least it won't hurt!), then see what the next scan shows. In the meantime, maybe ask your doctor if you can do a blood test for HCG level to get more clarity, because sometimes the lines don't lie but they're just too faint to read properly. Stay strong, the waiting game is tough but you'll know soon!