Breastmilk storage

So my consultant didn't really tell me much about how to store it so I've just looked it up and gone from there but my concern is can you go from the freezer to the fridge? And if so how long is it good for? I exclusively pump so normally what I do is set the frozen milk out the day before let it thaw then put it in the fridge for the following day. But sometimes I'll have some milk leftover for the next day as well. So would it still be good? How do you know if milk has gone bad?