I second the idea of more daytime sleeps. Babies are wierd, the more they sleep, the MORE they sleep. Keeping them up just gets them overtired, oversensitive and over EVERYTHING!

Kates tag team approach is great - we did that too as there is only a certain amount of yelling anyone can take. I'm sure it wont last too long, stick with a routine even if its loose, she's pretty young to be in a routine yet but she will pick up on dark time quiet = nigh nighs after awhile.
Why don't you see if you can pick up a copy of Dunstan Baby Language? It came out when my kids were older but I saw it on Oprah and I was pretty impressed.

Please, please don't second guess yourself about holding bubs alot - its what she needs. She may respond to patting and ssshhh sssh ssshhhing when she is in her bassinette too. Being held MAY overload her, its hard to say. But keep close to her.

It made it easier on me when I thought in longer terms (hard during the still of the night, I know!), ie I will try this for 2 weeks or a month and if it gets better within that time woo hoo, if not I will try something else.

Hang in there mumma xoxoxoxo