my dr thought i was 7 weeks and i new i wasnt, as my cycle is not 28 days,

i had a scan a few days ago that said i was 5 weeks and 5 days and i heard a strong heart beat also was 144bpm, i was worried and nervous to but it all worked out so you should be ok, and if they cant detect it, they will get back in a week or so to try again, at least its a starting point to work out dates