From the waterfall, looking towards the statue, there is one nest close to you, low down above the river, and behind that, another to the far back on a platform, near the statue's right foot. At mid distance, there is one nest to the right, high up on a platform, and one off to the left, slightly higher than the nest above the river, and slightly closer than the nest on the right.
If you really only got 3 nests, do you have a save before entering the Hall of Echoes you could reload? If not, maybe exit the game and restart, hoping it was just a glitch loading the first time.