Yep, my stomach was h-u-g-e!! Normal fluid at delivery is around 300mls, I believe. I was told mine was around 3 litres! And a 4.2kg baby. I measured 8-10 weeks ahead from 22 weeks (and yes, that means I was full-term size by 32 weeks and still growing!) No GD, no PE, no problems with bub (although we didn't know that for sure until birth). It was just one of those things.
From my experience, fluid levels can change pretty quickly. I had my 19 week scan and the report said fluid was normal. In the weeks following, I had heaps of people saying I was looking "more pregnant" but just figured I'd "popped" out. Saw my OB at 22 weeks and he noticed too. A quick scan and measure and next thing I know, I'm off to the specialist maternity hospital! I don't know about ctg monitoring. I had monthly, then fortnightly ultrasounds.
Scary, scary time but both bub and I were fine in the end. I hope you get the monitoring and care you need and that you have an equally positive outcome.