If my appendix was on the left side, but my heart is also on the left, do I have situs inversus? Would/could other abdominal organs be transposed too?

Not necessarily. Situs inversus (changed sides) can be partial or complete. As the intestines develop, the eventual location of the large intestine and other related contents may also be flipped.A process called a laterality sequence may have duplicated or absent structures (spleen) and heart defects. You likely had an isolated anomaly. Further study could confirm or exclude any associated abnormalities.