When you find out what's causing that, be sure to pass the info on. I never lost weight after my gall bladder removal and I sure could stand to lose some now (seeing how I can't fit into last summer's shorts!).
Before I got my gall bladder out, though, I did lose quite a bit of weight quite rapidly. I went from wearing a size 14-16 to wearing a 10 in less than the course of my spring semester in college--so less than 3 months. That was due to me just not eating because everything I ate made me feel sick to my stomach. Also, I did have diarrhea problems, and that can cause, as you suspect, absorbtion problems. So if you're still having adjustment difficulties after the surgery, you're not eating much, having diarrhea problems, then you might want to give yourself a little more time to see if you get adjusted. Since you mention you have weight to lose, it shouldn't be dangerous for you to lose so much (although, I will warn you, it's probably not a sustainable weight loss--mine wasn't).
You may find that you are just not hungry anymore and that's why you don't want to eat. A lady I work with said she had read that the gall bladder helps regulate appetite and that your appetite can swing wildly in either direction when you don't have one. Given that she's a stick woman, her lack of a GB apparently causes her to not be hungry very much. Me, on the other hand, I have a hard time feeling full and so overeat a lot.
You should be about through with your post-surgery adjustment period, so if you are still having problems with diarrhea now, that's not likely to go away on it's own. If you don't have a lot of diarrhea or have it frequently, you may be able to get by with just taking calcium pills daily to keep your stools firmed up; that's all Inape needs. Me, I have more D than the calcium alone can handle, so I have to take Welchol. It's a cholesterol medicine that has the odd side effect of absorbing your excess bile. If you're having a lot of D problems, then go see a GI and ask for the Welchol for your D. Once you find that you no longer get sick everytime you eat, you will soon be eating well again (and probably gaining that weight back).