I've had the same issues as you. My LO is slightly over 2 weeks and starting to be more alert for feedings but still falls asleep most of the time halfway through feeds. I also have other issues though such as large breasts, large flat nipples and baby's head measures small so her mouth is small as well. I'm mostly pumping until she gets a little bigger but have been told to try and do one successful feed a day to help maintain supply even if I have to top off with bottle. Always pump after a successful feed as this is what will up your supply. Massaging while bfing or pumping (start from top of breast and work down to the nipple, I use my thumb) also helps with this problem as does a warm compress for 15 mins before pumping will help with the letdown.