Sayang, polyhydramnios (air ketuban lebih) memang boleh happen even without GDM, alhamdulillah you're negative! A few of my mum friends experienced this too, and honestly the docs just monitor more closely la, sebab bisa affect labour timing. Since baby size okay, that's a good sign, tapi you really should discuss dengan your doctor what they want to track moving forward, kasi peace of mind you know? Did they give you any specific instructions or just say monitor? Hang in there, most cases resolve fine, but this one kena follow-up closely dengan specialist.