Differing measurements

I have a questions regarding measurements. According to glow I am 33.3 weeks. This has been accurate as my doctor has been measuring me bimonthly at each appointment. Earlier this week I saw my doc and she said I was measuring a week behind. Although she said she isn't concerned she still decided to send me for an ultrasound. I went to my ultrasound today where the tech said I'm measuring at 35 weeks. I don't know what to make of any of this. Does this mean I will have him earlier than anticipated? Thanks for any response. Your input is greatly appreciated.