Eh, at 38 weeks memang normal rasanya confusing between discharge and amniotic fluid because both boleh increase! Since your last scan showed normal AFI at 15, that's a good sign la, tapi kalau you're worried, best check with your doctor lagi bila next appointment, especially since this has been happening since 34 weeks. A few of us in my mum group went through the same thing and our doctors just did a quick check (sometimes dengan nitrazine paper or just visual) to confirm, so it's worth asking your OB/GYN to clarify je, terutama since you're so close to delivery now!