personally i suggest stalking the SW website.
i watched flight prices for a particular set of dates i wanted for a month and almost every day the prices went up and down and up and down and then went down a fairly sugnificant amount which is when i booked.
its very likely that they will play around with the prices for a while for the end of may.
so i would just wait it out for a little while to see if the price comes down.
i also noticed that it seemed to be between 2am-9am that the prices were lowered and then it seemed like they'd go back up for the rest of the day.
i don't like that airlines play games with us but i do like that i play along and beat them lol.
also i believe your party size can be considered for group rates which can sometimes come with a discount so i would look into that.