Recently, my iron level has been pretty low (so I can't donate). I was thinking about eating meat once again. Is it worth sacrificing veganism to become a blood/platelet/plasma donor, or should I rather continue being vegan instead of donating blood/platelets/plasma?
There's certainly a degree of iron supplementation that needs to be done under a physician's guidance. But I've never seen anything suggesting that supplementing to the extent of a common multivitamin (18 mg/day) needs particular medical oversight.
If you're low iron on a vegan diet, you might or might not have other deficiencies as well (e.g., various B vitamins).