I cannot believe that it's only been three days since we saw the baby! But we finally have proof now, and here it is:
And here's an anatomical picture for reference:
Our baby is mirrored to that image (just facing the opposite direction) and the black spot in the middle of him/her (near the head) is the beating heart. The black circle around the baby is the amniotic fluid inside of the gestational sac.
I love that little one so much! Isn't he/she cute! Btw, the scale on that picture is 3 mm between those two yellow dots (that means the baby was 3 mm long on Wednesday).