Selenium and Menstrual Cycle

[ttcintexas]

I was wondering if anyone knew if selenium could help to lengthen my menstrual cycle. 

I have gone from having approx. 30 day cycles to have 25 day cycles. It went down slowly but then seemed to remain pretty much at 25 days. I then began taking selenium for prep and follow up to having an amalgam removed. The two cycles I have had in this time period have been 27 days. Could it be the selenium? I had previously thought that fish oil had increased it, but then they went back down. I may be grasping at straws here, but I'd like my cycles to be longer than 25 days.

Also, I am wondering about how much is too much Selenium. I have been taking between 200 and 300 mcg of Selenium per day (300 when I remember to take my prenatal vitamin--not pregnant or nursing, just trying to finish out the bottle before switching to a regular multi-vitamin). I was going to stop the 200 mcg of Selenium as it's been almost 3 weeks since amalgam removal. If it's helping the cycles, though, maybe I should continue. Is 300 mcg in the ongoing too much Selenium?

Thanks.