We mainly use adjectives to describe emotions - happy, annoyed, angry, sad, miserable depressed, nervous, anxious, worried, upset, disappointed, offended and so on. We use them in the following type of sentences:
I'm ...
I'm feeling ...
We can make these statements sound more natural by adding modifiers. For example, to soften the statement you can say
'I'm feeling (a bit/a little/quite/rather/pretty) unhappy at the moment.'
or to intensify it you can say for example:
'I'm feeling (very/really/extremely) unhappy at the moment.'
We also have 'extreme' (non-gradeable) adjectives which can't be modified in the same way. These have their own set of intensifiers, for example (absolutely/totally/completely) ecstatic, delighted, terrified, furious.