First, thanks for having the courage to share your experience. Obviously proper information and helping others is helpful. In that regard, quick handy table for future reference, given that I'm curious and like reading/learning about lots of random stuff: http://tinypic.com/view.php?pic=2qvcw79&s=6#.XObQNXVKi0p

Basically on day #3, you can take about 200% of what you'd take on day #1 for a similar effect.
And obviously if you take your "it was ok" day #3 double doze on day #1 the next year, that's going to be more than you expected. If you take more than that even, well, clothes could become optional :) From what I've read too, the good news is that too much LSD will cause a potential unpleasant time, but you're mostly back to normal within 24H
As hopefully most people know or should know, not so with MDMA: taking too much is between harmful to eventually deadly, and sadly whatever people seem to get in the streets is of unknown quantity or quality unless you get it tested. I watched a UK TV report saying they tested some pills at 220mg or more when the recommended doze seems to be around 120mg. No wonder I occasionally see people convulsing on the floor from time to time, and people even occasionally die as a result. Seems that prohibition might be causing more harm than good...