Going by fundal height I was measuring 5 weeks behind at 34weeks. My MW wasn't concerned because she finds using the actual measurement as a guide is inaccurate and prefers just to go on how much it grew from last time using land marks.
As for weight, are they weighing you same time of day with same amount of clothes on and same scales etc? Because all those can impact weight measurements.

Anyway hopefully it is nothing to be worried about and all is ok.