If you need to donate more frequently than 8 weeks, you could search for a local donation center that's not affiliated with the current center you go to. Just don't over do it and get your hematocrit levels low in the process.
I have to donate on a regular basis to keep my "hematocrit" levels normal. I'm able to do it more frequently, as I'm on Dr. directed orders to do so, as part of TRT...typically donate ever 5-10 weeks, depending if I'm cruising on TRT or blasting.