help!! I am worried 😣😣😣

I had a routine 20 week anatomy ultrasound on Friday. The tech told me she saw a white or bright spot on the baby's heart. Otherwise, everything looks perfect. I got so worried, i started crying. She didn't tell me anything more about it. I have an appt. on Wednesday to see my doc. Is this something i should be worried about? I read it could mean down syndrome but i got the test for down syndrome and it was normal. On top of that, they also said my cervix is measuring a little shorter then they'll like it to be, between 3.4 and 3.7. Is this concerning? I tried calling the nurse to ask these questions but she out on vacation. Anyone else have been in a similiar situation? I'll attach a pic of my baby girl in a Hd ultrasound i got at 18 weeks. I think she is perfect.