I wouldn't stress I'm tall and at one point I measured 44cm at 37 weeks baby was born at 39 8.9lb and my scans certainly didn't show a massive baby. I have a tall back and she was lying in a way that made my fundal height more than it should be. I rarely measure as I should either. My baby that came at 38w at 9.7lb I only measured 2cm more very odd. It can be down to positioning too which is why they double check with a scan