I would go by the scan at this stage there is a big difference in what you can see between 7 weeks(fetus with hb) 5 weeks most usually gest sac or maybe small fetus they are usually max about 5 days out at this stage but with 2 weeks difference I would go off the scan as you can o late and the dates really start from 2 weeks before you o but not everyone like myself has a 28 days cycle

wish you a h&h 9 months and when you are holding your bub 2 weeks won't mean much