Basically the way it is currently configured, we are searching on historical data UP TO 24 hours old. Without getting into the technical details, we made the choice to reconfigure the way vBulletin's search works in order to maintain optimal performance for the site overall. As such, new posts will not work (as the returned data would always be older than your session time, which is 15 minutes) and you won't see any posts you made since the last search database update (every morning between 4:30 and 5:00 am CST).
I'm thinking up ways to return those two features while not hurting performance. With 2.1 million posts, intricate searches can tie up the database - which will cause EVERYONE else on the site to wait until the search completes. Some other sites can get away with searching large databases, if their queries are very simple or very repetitive. LS1Tech is a technical site, so our queries are rarely the same and often very targeted.