14 month old only sleeps when nursing

I really need help. My 14 month old will only sleep if I nurse. If we rock or cradle her she screams and kicks until we put her down. She does not take bottles. I'm pregnant with my second and really need to wean her off the breast. She nurses for her afternoon nap, bedtime and mornings when she wakes up too early. We also cosleep because ever since she was a baby she refused to sleep anywhere else. Please any tips for how to wean her?!