Google is a good friend, the roads are horrible!
Better yet, solicit a friend who knows how to get there!
It is a slow drive!
I am not familiar with Point Reyes, so Google is a better friend on this Waterfall. It's a slow drive, go early, if you are headed there on a Saturday or Later in the evening.
If you walked more than 5 miles you went too far. About 5 miles is where I would look for left turn into Alamere Falls trail. It isn't obvious turn and it looks like you are diving into the bushes crunching down. Don't be alarmed. It's the right place. There are lots of poison oak, be careful and cover up.