plasma vs interstitial fluid vs lymph T-T.... I know they're all similar but different but I don't know HOW

They are all related, but differ by where they are usually located in reference to surrounding tissues [* see "fluid compartments"]. They also differ in their general functions within the body.

Blood is generally comprised of red blood cells that carry oxygen, platelets that help with clotting, and white blood cells that neutralize or decompose harmful substances. Plasma is the liquid part of the blood that holds them.

Interstitial fluid comes from blood plasma. As its name might imply, it exists within the spaces between cells (the "interstices") and allows tissues and blood to exchange materials. Interstitial fluid becomes lymph as it enters the lymphatic system. Lymph is filtered by lymph nodes and carries certain types of white blood cells (lymphocytes).

Broadly speaking, the cardiovascular system and lymphatic system work in parallel to deliver nutrients and remove wastes to all other cells by transporting extracellular fluid (i.e. all of the fluids outside of the cells, which includes blood plasma and interstitial fluid).

letslearntogether haha yeah I was being a bit hyperbolic. Thanks for your explanation!