You should definitely call the lactation counselor if you haven't already. They will give individualized advice that no one here can. In addition, they will also provide some reassurance that your baby IS getting enough to eat, that you are doing ok, and that your baby is going to be ok. Call them.
In the meantime:
1) Tickle the baby's feet
2) Change the baby's diaper (you probably need to anyway)
3) Lower the lights. (Babies are used to total darkness and will close their eyes in bright lights, which obviously encourages sleep)
4) Undress a bit of baby here and there. The jostling disturbs them as well as the cold air. Don't completely undress, just expose an arm here and then a little chest there.
5) Try an "unfamiliar hold" such as the football hold if you've been doing crossover, or vice versa.
6) if your baby favors one breast over the other, offer the less favorite one first- she might stay awake for a "second course" from her favorite.
Those worked for my sleepy babies. That being said, newborns only nurse for a few minutes tops anyway, so make sure your expectations are realistic. AND, as your lactation counselor most likely mentioned, they only NEED a few minutes anyway.