My birthday also falls on Mother's day weekend, so Sunday's out. (My birthday is actually on Monday, May 15th.) The 13th is my name day, so it makes a good day for a party anyway. Anyway, this is just a preliminary testing-of-the-waters to see what I might want to start planning.
I could come to your party if it were
In Portland on Friday the 12th starting around 8 or later
In Portland on Saturday the 13th in the afternoon
In Portland on Saturday the 13th in the evening
In Eugene on Monday the 15th in the evening