SO confused!!

Ladies, I need some help. 
I'm supposed to be 10 weeks pregnant as of yesterday. My last period was February 28th, saw midwife for first appointment yesterday and she couldn't hear a heartbeat but wasn't concerned. I went for a dating ultrasound today and the tech said "how do you know you're pregnant?" And "are you SURE you've missed your period??" Because she couldn't find a baby - she said if anything, I COULD be less than 5 weeks pregnant but she didn't see a baby. I didn't get other details. I had an extra pregnancy test at home, so I took it. This was the result within literally 15 seconds of taking it. 
I'm assuming a missed miscarriage? Anyone have a similar experience? I'm super confused and wondering what's going on....