Donating Bloodplasm - Yes or No?

My flatmate went to donate Blood and Bloodplasm and he said it's cool and i should try it. Well since i want to help others i tryed a couple of times. My first blood donation went well but then they wanted my plasm and i really have weired veins. They keep rolling away. They found it and want to get the needle ready and as soon as they try to get me all set up my veins just roll away. I know it sounds funny but it actually isnt that funny. The first time with the bloodplasm was ok i guess, they tryed my right arm because usually they wont get anything on my left side but right wouldnt work that day so i'd to move to a different chair so they could try my left. It worked. I got a bruise on the right side but it didn't hurt. A week later i wanted to go the second time and i told them they should use the left (because it worked last time)...well it wouldnt work, my veins just rolled and rolled, they didn't catch one. They said they try the right arm again after trying on the left about 5 times. Since i still had that bruise they couldn't use the vein they wanted and took a different one more visable... well the thing what happend was, the lady who did that was full of my blood and the venous valve kinda messed up. So i couldn't donate that day, i got one with two more bruises and two arms in pain. But i still didn't give up, a week later i went a third time. They did the left side again and it worked perfectly....at the beginning! After donating 1/4 bloodplasm the needle stoped working and my blood wouldn't get through. They tryed my right arm again and it worked. Ok i had two in needles, one on the left and one on the right - yeah that really is something i like - not! Since right worked they wanted to get the left needle out of my arm and they made a mistake (lady was full of my blood again) and it hurted like hell, i can't describe the pain. I will post a picture of the huge bruise i have now and it still hurts really bad. So i don't know what to do. Should i go one more time? I really want to donate it, first i can help and second we get money for it, and i could really use that money. I mean it worked on the right side, so should i try a next time? I look like a junkie so. I just don't know - any suggestions?

This is my left arm, the bruise is even bigger and blue/green/purple (the cam doesn't show it correctly)