The only Disney event that month is the cruise May 16-19.
And you do know about Friday nights at the Contemporary and Saturday nights at the Poly, right? If not, here are the details. DIS member Pintrader has organized not one but two great weekly pin meets. One is Friday night at 7 PM on the 4th floor of the Contemporary by the pin station. The other is Saturday night at 7 PM in the lobby of the Polynesian by the pin cart. Both attract quite sizable and regular crowds and the atmosphere is VERY friendly.
Also, don't forget about Scoop's seminars. Last I heard, they are held at 1 PM Sunday thru Thursday at Expo Hall in the MK (someone please correct me if the days and times have changed). As you enter, go to the left past the pin display and near the photo booths. Scoop gives a great and popular seminar on pin trading etiquette and the making of pins. Afterward, a pin meet inevitably occurs.