Breast Feeding and Work Help

Rachel
I go back to work in a couple of weeks.  My little one will be 12 weeks old. Does anyone have any advice for this scary transition? How often and how long do I pump? How do I know if I'm going to pump enough to send to daycare?  If I have a Medela pump and my daughter uses different bottles should I pump into bags and avoid having twice the amount of bottles to wash?