My favourite phrases for happiness are:
I’m on top of the world.
I’m on cloud nine.
I’m in seventh heaven.
And for sadness are:
I feel really down about it all.
I’m feeling very low about it.
He’s down in the dumps today.
Macmillan Dictionary has a list of more phrases you might like to use: http://www.macmillandictionaryblog.com/language-tip-of-the-week-feeling-happy