Baby size not matching date

Claire • 5 miscarriages, praying for my rainbow :(
So yesterday I went for an early scan due to recurrent miscarriages, I was supposed to be 7 weeks (my cycles are like clockwork & I was testing for ovulation)
​They have said that my baby is measuring 2.4mm which would indicate that I'm only 5-6weeks & they weren't able to see a heartbeat because it's so small. I have to go bk next week for a follow up scan. The nurse told me that sometimes the dates just don't match & to try not to lose hope.
​Has anyone else been in a similar situation to this & had a positive outcome? x