Anatomy scan, at 19 weeks + 3 days

I had an anatomy scan about two weeks ago. The tech was able to measure my son’s legs, arms, the head, abdomen. But she couldn’t get a decent profile nor a image of his heart because of the way he was laying. She had me try laying on both sides, and even walking up and down the hallway twice to see if that would help, if not I’d have to come back- it didn’t. So afterwards, I see a midwife. She says everything looked normal. Read off what the tech measured during the scan. The midwife said the tech wrote down that she saw calcium on a part of his heart. 🙄. So on the 6th I have to go see a fetal specialist to get more photos of my son’s heart to see if it’s still the same size, disappeared etc. I just don’t understand how she could had seen a calcium issue, when she was having difficulty getting images of the chambers of the heart and everything? I even went to a private scan at 17 weeks, the woman that did the scan saw his heart perfectly. I had to write down my physicians info just in case something wasn’t right during the ultrasound, yet the tech that did my private scan said he’s healthy. She would had seen a calcium deposit on his heart then... I’m just confused and worried. My midwife said it’s a marker for Down syndrome. Anyone ever gone through this?