desperately need help 😢

Hi ladies, here is my situation: I took a test a few weeks ago, turned out to be positive. I used the clearly digital (the ones that tell you how many weeks). I had all usual pregnancy symptoms (sickness, sore breasts...). Went to my ob/gyn on Wednesday (we estimated that I was about 6 weeks 5 days according to first day of last period). The scan showed an empty sac :( according to the doctor, there is no baby. I'm having a very tough time accepting it and I'm torturing myself hoping I got my dates wrong and that maybe the embryo was too small to show? Is that even possible? I know for sure that I had implantation bleeding on the 22nd may. How old is the embryo when implantation happens? And how many weeks would I then be with that in mind? Sorry for the long post. It's just such a rubbish situation to be in.