Sounds like you should worry abt your Drs office not the baby. Mm4 pregnancies mine never changed.. Which is somewhat normal as u get towards half way, but that much that frequent is a bit overboard 

2 different Dr's offices. The first date was based off my last period. The second date was changed with the first ultrasound. And now today at my new Dr the baby is measuring 1.5 bigger so they gave me an earlier Feb date.

Mine has never changed

With my first I hers changed once it went from Dec 25 to Jan 3. My second never changed and now with my third it hasn't changed either. A month is a big difference. I would be asking a lot of questions as to why they're changing it...

A month change is significant, I'd question it.

They changed mine from 2/ to 2/14 at my 9 wk ultrasound that's been it so far

Mine hasn't changed ... Now 19 weeks ... We will see what they say when we go to the next appointment at end of september

I'm 19 weeks and in the first 12 it changed 3 times. I personally still think the first date was right but it only ever changed by 9 days at most.