I'm a bit upset about this year's bonus.a bit of还是a bit?

I'm a bit upset about this year's bonus.a bit of还是a bit?
a bit “一点点，有点”，= a little,修饰形容词、副词；也可以作宾语、表语。
eg.I'm a bit tired.我有点累。
I ate a bit.
但要注意：not a bit = not at all “毫不”
not a little = much 非常
eg.He is not a bit tired.他一点儿也不累。
He is not a little tired.他非常累。
a bit of = a little,放在名词的前面，作定语。
eg.I have a bit of water.= I have a little water.
3.quite a bit 相当多