A word of advice on yarn: could be dangerous if the cat ingests it. I have one cat who goes nuts over ribbon and I cannot have any out and about the house or she will eat it. Things like ribbon, string, yarn can wrap around the intestines and/or cause blockages.

Are there cats outside of your house? Could you be picking up their smell when you go outside? Are you spending a lot of time at a place that has other animals and bringing the smell home on you? Cats react to smell more than sight, so if you are bringing strange smells in, it could be part of or the whole problem. Also, if your cat is seeing stray cats outside, she could be misdirecting aggression at you because of seeing them.

You might want to research Feliway and try some.