Flat nipples

Any advice for breastfeeding with flat nipples? My baby girl is a week old and she doesn't even want to latch. She gets so frustrated and pulls away right away. So I've been pumping and giving her a bottle for the past week but I don't want her to get used to it. The nurses also said I have big nipples and she has a little mouth so that's another issue. I really don't want to give up but it's so hard!