Undress your LO and let her cool off some, feeding in only her diaper. Also if you can feed topless, skin to skin helps stimulate. Babies won't sleep if they are cold. Also wait to change diaper until she starts getting a little sleepy and then change her. You could also feed her with bright lights on and when she gets sleepy play with her feet, rub and lift her arm and stroke her cheek. Also break latch and set her down until she wakes up and then relatch. You have two things going on, she's cluster feeding to up your supply and not much you can do about that but newborn are also really sleepy so they often fall asleep before they are satiated. Stimulation is the key and its a lot of work.
If you aren't worried about nipple confusion you could also express some milk, breastfeed her and then top her off with a half oz to oz of bm in a bottle for that last feed before bed. That way you might get a 3 hour block to sleep before she's hungry again. Unfortunately some of this you just have to go through but it does get better. My daughter is 4 weeks and has a couple of 5 hour shifts now which I take advantage of when I can.
