Anybody know of any good QGD repertoire book that covers the Catalan? I can't believe I haven't found one that does. Should I switch to the Slav?

The Catalan is normally considered a separate line from the QGD.  You will need a different book for it.  Which QGD are you playing?  Right now the slav is generally regarded as giving black better chances than the QGD.

"Winning with the Catalan" by Angus Dunnington.

"Play the Catalan" by Davies is supposed to come out this month!

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I play the Tartakower , sometimes I throw in a Tarrasch or Cambridge Springs.

I like the QGD from both sides but I find the Slav gives greater opportunities, as well as greater risks, to Black.  Used to be when I was playing up and only wanted/needed a draw I would use the QGD.  Nowadays, playing up is Masters and they know how to grind out the White side of the QGD.

Most books about the catalan are dedicated to it. It's actually seperate from the QGD. Also the Catalan is a White opening and a Black defence. "Play the Queens Gambit" by Chris Ward covers most QG stuff. But he picks lines he thinks are aggressive so you don't get the whole picture. He only covers aggressive lines like the QGA 3.e4 and QGD exchange for example which is great for the attacker but not for the positional player. He does cover all ground there though. No Catalan though. This book is more of an attacking d4 book more so than an all-round book. It's great if thats what you're looking for.

This book should help you out, although its quite theoretical and not so explanatory.

Here's a review.