My EDD is the 20th of May.
How did I figure this out?
Well - since I have been charting my fertility I could pin-point my date of ovulation based on my BBT (thats basal body temperature). Because I know when I ovulated, I know the soonest possible time that I could have concieved. I can then figure out my when my baby would be due based on this and the knowledge that the average pregnancy is 280/266 days long.
I used Prem's Rule to figured out my EDD.
Here is a good website in helping you figure out your EDD to the best of your knowledge! I found it very helpful!