Ultrasound question.

Ok, I am seven weeks(according to my LMD), I went in for a quick ultrasound today(had a mc in December)and they said they couldn't see very well because my bladder wasn't full enough to push my uterus up. Has this ever happened to anyone? I understand my baby is still so so tiny, so it's going to be hard to see anyways, but I've never even heard that a full bladder would help see the baby. The nurse says she isn't worried because she thinks she saw something but my uterus was too far down to see anything. I go back Thursday with a full bladder to see if we can see it again, and if not then we will go next Tuesday to a radiology place and probably get a transvaginal. So again, if this has ever happened to anyone, feel free to let me know the outcome-I'm hoping they've all been positive. Thanks y'all! Today has already been a bitch!