Hey guys. I need advice.

So I am currently 34 weeks. But the last two apps I have been measuring ahead with fundal height by 3.5 weeks, all of a sudden. I know people say fundal height isn't accurate (is that true) I'm going back to my early US and wondering if they look further ahead then they said. The first is my 8w3d one, does that looks 10+ weeks, or does it look 8? The second is my 9w exact one. Or does that look 10+? Thanks for the advice. What we're all your reasons for high fundal if you had the issue?