I've been exclusively breast feeding my 4 week old baby, but yesterday I gave her some formula. She was 9lbs 5oz at birth and is a very hungry baby, often having huge feeds every hour or so (she's gaining lots of weight). I know that's normal, but I was hitting the tiredness wall and needed some help. Today my breasts are very big, hard and tender. Does anybody have any tips on getting established with mixed feeding, and dealing with tender breasts? Please don't give me a hard time about introducing formula though! I intend to breastfeed most of the time, but want to give her formula a couple of times a day. Any advice from somebody who has been there gratefully received!