For us, weaning happened when DD started dropping feeds, dropping interest, and shortening the time it took to nurse each session. It happened over a period of months. It started very early, at around 13 months, and very gradually. She was finished at around 18 months and kept telling me "no, no nurse" whenever I offered. I was told by several people that it's just not possible at such a young age, but it's been a while now and she has never even tried to come back to it again. I offered for a couple of weeks and then gave up because she had no interest. Now when she sees them bare she will sometimes pat them and say "nurse" but only kiss them and then say "all done!" and scamper off. It was much less painful for her than it was for me! I wanted to nurse for much longer.
I would say that your son sounds plenty interested in nursing still, so continue to go at his pace and keep offering. It's not something that happens overnight, but rather over months. But, I guess all kids are different and there will be other advice coming your way. I would assume that if his interest was tapering for months that's different. Going to a party and being distracted from nursing doesn't sound like it's the end of a nursing relationship. I wouldn't take any herbs to dry me up - in fact, I was quite sad that I lost the milk I had when DD did wean.