Need advice

Ok so i went in for an emergency ultrasound because I was spotting for the past week. Based on my last period (April 14th)

im supposed to be 8 weeks but im only measuring 5 according to my doctor . I had my blood drawn and she called me saying they are exactly where its supposed to be for a 5 week ultrasound so she has a little more hope. My dates just don't match up. I have really long cycles and don't usually get my period on the date it says I'm supposed to. I'm soooo beyond worried . If this has happened to anyone please please let me know. Im just so confused because when I took a pregnancy test like 2 weeks ago it was sooo dark .