I honestly don’t measure the blends…. if there are instructions, please abide by them, haha. I just typically sprinkly the top of the hay pile so that’s definitely less than a full handful just grabbing from the bag, but more than half a teaspoon, so I don’t think you’re giving a ton at all. That being said, I would say that “nervous lately” is something you want to address behaviorally/environmentally rather than from the effects of the blend, since that won’t really solve the problem. If it’s due to environmental changes, trust with you, etc., you can give time and effort in helping your rabbit feel more secure and less nervous in the environment. Rabbits are prey animals, so nervousness is part of the mix and is an expected reaction to a lot of things.

Anecdotally, Zen definitely chills out both my buns and I know another rabbit owner who has seen it chill out their two buns as well.

No experience with this one, but I have used Serenity Snack from the BB store. It definitely has a calming effect, but I would say what you witnessed is probably more on the extreme end. Then again, chamomile is used in “bedtime” teas for people.