2 weeks behind

Hey everyone, I went for an ultrasound as I was having some spotting, according to my lmp I was 7 weeks, the a&e doctor performed a vaginal ultrasound and said I’m probably a couple of weeks behind but that she could see the fluttering of the heartbeat. I don’t have my first proper ultrasound for a few weeks still. But I’m just wondering should I be carrying on counting my weeks according to lmp or a couple of weeks behind ? She didn’t tell me what the measurements were either I’m very confused and not sure if I should be worried or not ..