Go to 'My Preferences' and look in the address bar at the top. It'll say something like http://forum.thesims3.com/jforum/user/edit/345514.page
Make a note of those six numbers at the end- they're your unique user code.
Type this into your address bar: http://forum.thesims3.com/jforum/posts/listByUser/******.page replacing the stars with the number you previously wrote down.
You should now find yourself with a list of all the posts you've made. It's a good idea to favourite the page for future reference.
Much easier doncha think?