EDD date

First time see doctor, GA based on LMP was 6w2d but sac measured 5w3d, so I readjusted to 5w3d. Second time see doctor, based on readjusted date was 8w2d, but baby is 7w5d w hb. Looking back versus LMP, the growth is slow by 10 days. While I know the dates can be off, is this 10 days a bit too much? I have a scan next week but I just Want to be mentally prepared. No symptoms kind of pg I am having so feeling even more worried. Thanks!