hi there, it is ok not to be fully effaced at 38 weeks you can safely wait till 40 weeks for the first stage of labour to commence. The gurgling sensation is beccause your stomach is pushed upwards by the gravid uterus
.During ultra sound
they do check the amniotic fluid index
and if it was less they would have informed you, so do not worry about that. If you are suffering from gesstational diabetise then there is apossiblitey of having a large baby and so do visit your gynecologist and get your self evaluated again if you do have a large baby then they will assess the possibility of your having normal delivary or whether interventiuon will be required. If need be they might even plan to induce you depending on your clinical exam. So the best thing to do now would be to get yourself evaluated and act according to your obstretitians advise. Take care.