I gave about a gallon. Last time I gave they fucked up my vein, said I had bad vein. Blood flow was slow because they fucked up my vein and needle wasn't even in right. When the saline or whatever got pumped back in it filled up a inch + tall pocket in my arm. They got me off the machine. People didn't have any useful information. The guy said "it should" go down in a day or two. The people were clueless sketchy and I'm never letting them touch me with needles.
I gave hopefully more than I'll ever need and enough to help some other people. Red cross still calls me sometimes, and I explain to them they aren't touching me with any needles. They should get their shit together and hire better people.
Oh well, my blood is my own now.
TLDR