Due date changed because of size of baby!

My original due date was 25th June, but I had a growth scan done on 19/04/18 and they have give me a EDD of 31st May going by the size of the baby.

I got abit worries cause that’s 3+ weeks of a difference, so I went to my GP and she measured my bump and figured out what way the baby was positioned and I’m measuring over the top percentile for my GA.

Has anyone every experienced this or can give me any advice?

The growth scan was a private scan I paid for that was very thorough so I don’t see how they could be wrong but I’m aware of my last period dates etc. Awful confusing also I don’t have pregnancy diabetes we’ve checked that.

So confused just want to know as it can be dangerous for my little pudgey growing away in there and I want to be in the know about what’s best and what’s going on.