5 weeks 4 days hcg at 2500 ultrasound tech couldn't see anything!!

I have struggled with infertility for 5 yrs now. The first time I got pregnant was almost 6 yrs ago which ended in a m/c. We have been trying to convince with no luck. This month I found out I was pregnant I was so shocked, scared and happy! Well my Dr has been keeping a eye on me because of my fertility problems and she sent me to do a ultrasound today to make sure the baby was in the right spot and everything looked good. Husband and I what to a place that does ultrasounds they lady that did mine was rude and cold! But as she's looking she asked me "are you pregnant"? I said yes as of yesterday my hcg levels were 2500! She keeps looking then she says "I don't see anything that would indicate a pregnancy" after that didn't know what to say I was trying to hold back tears...... And she had nothing else to say after that!! Has this ever happened? I'm so scared of a ectopic pregnancy!