31 weeks or 33-34?

So this Wednesday I will be 32 weeks...Or so I thought! I saw my Dr. on Saturday and he measured me and said I was measuring bigger..When I had My first ultrasound around 14 weeks it said I was Due 9-13-2009. Then I saw my doc who said they were fairly inaccurate and that we would stick with my 9-23-2009 due date. So thats where it has stayed..I had my next ultrasound around 23 weeks and my due date was 9-9-09 I thought pretty neat..But the doc stuck with the date of the 23rd..So I got used to the idea and dealt with it. Now I go on Sat and he says "so we are around 33-34 weeks now"..and I said "actually 31"..he says " how do I keep messing that up" he looks at the ultrasound and measures me and says that I've filled in and its looking more around the 13th..But just to be sure in 2 weeks when I go back he is going to send me for another ultrsound just to see..So I'm excited about that..Kind of stressed out I've possibly lost a few weeks..But thats ok..Just gotta get busy and get used to what life will be like with 3 little ones.
I'm excited, but nervous and stressed out all at the same time. I know things will work out~ I was so stressed about how things would be when I had 2..now I think adding one more will be ok..Infact I know it will be.