Evie Fraser has two right lungs, her heart is on the wrong side with four life-threatening defects, and her liver is in the middle of her abdomen, pushing her back-to-front stomach out of position.
Her intestines are also the wrong way around, she has no spleen and scans have yet to confirm if she has an appendix.
Doctors initially thought they would need to operate within the first month of her life, as she has no blood going to the left side of her heart.
Her parents Lyndsey Houston and Ruaridh Fraser, both 27, had their daughter christened by the hospital chaplain when she was three weeks old.
But as she approaches her first birthday on Sunday, Evie has amazed everyone with her incredible resilience.
Miss Houston, from Saline, Fife, said: "She really is my wee miracle. I can't believe she's doing so well without surgery. She's amazing.
"When she was in intensive care one of the consultants said it was a miracle she even survived in the womb.
"And here she is, still thriving.
"You wouldn't tell there is anything wrong with here. She's always smiling and everyone who meets her falls in love with her instantly. I've never seen a baby as happy as Evie."
Evie was born with right atrial isomerism, a condition so rare that there are thought to be only two other cases in the UK.
Her lungs are a mirror image of each other, with the left one formed as if it was a right one.
Her heart is also on the right side instead of the left and has four major defects, including a large hole, no blood vessels connected to the body's main pumping chamber, and no blood being pumped to the left side of the organ, depriving it of oxygen-rich blood.
The fourth anomaly is a narrowing of the pulmonary artery, which pumps blood to the lungs – a defect which would normally be life-threatening but is helping to reduce the pressure and amount of blood going to Evie's lungs.
Miss Houston knows that Evie will need major surgery this year to prolong her life, but the older their daughter is when she has the open-heart procedure, the better chance of success.
She may also need a heart transplant in the future.