breast feeding ahhh

So I am breastfeeding and baby is doing okay with latching she just falls asleep and quits on me. I'm usually able to get her back on trAck but sometimes I just can't wake her back up (the past 2 nights she has been wanting to feed and then oasses out after a few min. I don't think my real milk is in yet but my boobs have doubled in size and just feel really hard!! The consultant said to wait to pump until the real milk comes in but do hand expressions but it still doesn't do much!