As Debi said, you should have stretched it more. Stretch it and wrap it over itself (kind of like kneading it in the air) until the surface looks smooth and shiny. I have to reheat mine a few times, normally, until it gets to that stage.
I think your consistency will improve with the stretching. My mozz would just crumble if it weren't heated and stretched several times.
As for the keeping quality, what recipe did you use? The citric acid method doesn't keep very long, usually 4-5 days in my experience, but as Debi said, it could also be because it was too wet/not stretched enough to get all they whey out. Cultured mozz lasts longer, but I still freeze mine if it is going to be longer than a week until I can use it.