Shouldn't this be eu estou feliz rather than eu sou feliz because emotions are transient, not fixed and permanent.
Thanks Davu never quite thought of it like that but your explantion makes perfect sense.
One of the positives of having three verbs for "to be". They are more nuanced :)
I shouldn't worry too much - learning a foreign language is a really good way to learn about your own. Quite a few of the discussions here are more concerned with English grammar than they are with how things are expressed in Portuguese.