I'm also a regular blood donor. Even though my blood isn't the one they want the most (AB+, so the need is not great), it feels good to donate and be able to help. It's also good for my own health to donate blood, like you mentioned, so why not?

I've also been in a situation where my hemoglobin wasn't high enough, but then they tested it again, twice, and saw that the first test was inaccurate, and I was able to donate. I almost got disappointed there before they tested it again, it's never nice if your trip is going to waste.