Hi everyone!!! My last period was on April 14, and on May 19 I took a …

Hi everyone!!! My last period was on April 14, and on May 19 I took a test again and the result was positive, but the second line wasn't very dark — not faint either. On the 20th I went for an ultrasound; I thought I might have inflammation or a delay or some disorder! But the sonographer said that both the uterus and the tubes are clear, there's no inflammation and pregnancy isn't visible either. She told me to come back in five days. So I'm wondering, can that happen — a positive test but a clear ultrasound??? Has this happened to you????