Amniotic fluid volume is at 7.3cm

I am in my 34 week and 1 day. My last ultrasound was a week before and it read that there was one cord loop seen on the neck and my amniotic fluid was at 7.3cm. My OB gave me dexamethasone since yesterday until tom. Any advice if I can still increase my AFI? I am also scheduled for biophysical ultrasound tom. Hope you could enlighten me because I am really scared. Thanks.