R.M.
Oh my the memories that this brings to mind!! My first child breastfed every two hours, 24 hours a day for months and months it seemed like!!! I called myself the "human pacifier"...lol. I would suggest that you give co-sleeping a try...that way you can sleep while she nurses. Has the nursing schedule been this way since birth or is this something new? If it is something new she is probably getting ready to enter a growth spurt and this is her bodies way of helping YOUR body to get prepared by boosting your milk supply.
Does your birth hospital have a lactation clinic? If they do...make a visit and have a talk with the Lactation Specialist...she should have some great suggestions for you.
In the meantime...please don't give in to any temptations to supplement with formula...that will just be making the problem more complex because your body won't be producing as much milk...and your supply will become inadequate for her. Supplementing with formula can make breastfeeding SO much more complicated!!! If you are producing an excess of milk...pump...and freeze it to use when you go back to work!!