There’s LMP and gestational. I found out that I was pregnant when I was 7 weeks basing on LMP, but when I did my scan few weeks after that, base on LMP I’m 12 weeks but base on gestational, I’m 9 weeks. Gestational is more accurate as they will measure based on baby’s length and growth through the scans. Hope this helps! I was confused at first too, just like you. EDD will tend to change after every scan but the dates are not too far apart.
I think the lmp isn’t a very accurate measurement. But, keep calm and have a positive mindset! All the best