Leakycon reserved a block of rooms at the Crowne Plaza hotel. Did you check there?
http://leakycon.com/hotel
Also - before you buy an Annual Pass to get the room discount -- I assume you will want to go to the Leakycon event at Islands of Adventure on Wednesday night. They have been saying that it might be tied to park admission you buy specially for Leakycon. That didn't sound right to me, but they keep saying that if you have an annual pass there could be issues getting the ticket to this event. If you click on Formspring at the bottom of the leakycon website, there are a lot of questions and answers posted.
Play around with the universalorlando website, since your days aren't definite. Check for availability for the minimum number of nights needed for the discount (can't remember if it's 3 or 4). You might find that there is one day for which the Stay More Save More discount is not available. If you book earlier or later, you might be able to get the discount.
Sounds like Leakycon is going to be huge -- over 2000 people registered so far.