It is GOOD... that she is expressing herself.
At this age however, the emotions, are not fully developed yet and are still developing.
At this age, they are NOT articulate about it nor rocket-scientists about their feelings.
But the fact that your girl CAN say how she feels, is good.
As she gets older... she can then gain more ability, to be more specific.
I taught my kids about feelings and the names for it, from 2 years old. Over time they got more succinct, about it.
My son at 3 years old, could tell me the difference between him feeling 'grumpy' or 'irritated' or 'frustrated.' For example.
If he was sad... I praised him for telling me. Sometimes he didn't have a reason. Just like adults. That's fine. But I would validate him and just let him know I am there for him. And I would also teach him problem-solving... together with him. Because, a wee child cannot do that by themselves. So you guide them, on it.
If for example, my son was 'sad' about something, I would ask him "Do you want Mommy to help? Or do you just want to sit here and relax for a moment?
Or, if his toy was broken or something, he was sad. Then we would talk about it, together. And if I could fix it, then 'we' would.
Don't expect, your girl, to articulate her feelings, precisely and don't show her that you get frustrated. She CANNOT tell you, and 'explain' it.
Some 5-6 year olds, cannot do that either.
So keep your expectations, age appropriate.
Just teach her about feelings and the names for it.
In time like a rock collecting moss, a child will get more succinct and articulate about it.
Again, some adults can't even explain their feelings, so a 3 year old, may not do that either.
But teach her.... and guide her.
all the best,