freezing breast milk again?

just got home from the hospital and I exclusively pumped while there. I went home with a bunch of milk. they froze some and some already unfroze. I went to buy breast milk bags to freeze them but was wondering if I could unthaw the milk that is already frozen and put it into a bag to freeze again? or should I just keep the frozen ones in the bottle and put in the freezer? I figured the bottles would take up some space and my apartments freezer is really small.