I had the same thing as you when I was pregnant with my first bub.
I had an ultrasound at 19 weeks and they told me it was laying low so I had to have another one at 34 weeks and the idiots that did the ultrasound told me that it had moved up. But in my case NO IT DIDN'T.
It just means that you have to have bubby 2 weeks before due date by cesarian.
I was trying to have my baby naturally when they found that I was bleeding alot, the baby wasn't moving down and my blood pressure was through the roof. They realised that that the placenta was still covering cervix so she wasn't able to come out.
Its nothing really to be scared about......I know it means that you can't have a natural delivery but bubby will be coming out nicely anyway.
I am now pregnant with my 2nd (only 7 weeks) but I was told that I am to have another cesarian at 2 weeks before hand. As my placenta was actually attached to my uterus and they had to operate on me so this time around they will have to keep an eye on me. I'm not scared at all.
Good luck with it all!!
QLD, Mum to Chloe 16.05.04 + Caiden 25.08.06