How to help 4 month old sleep better at night?

Hello all! I'm a very happy first time mom to a beautiful baby girl. My LO goes to sleep at 8pm she usually drinks 4oz before bed (Brest fed only). Within an hour and a half she's up crying and we rock her back to sleep. She wakes again at 12,4,6 and up for the day at 8. Each time she wakes I give her about 2 oz. We were co-sleeping but she used my nipple like a pacifier, which BTW she won't take a real one, I have her in her crib and tried the no cry sleep solution by Dana Obleman but I can't do the cry it out she would cry for an hour and a half before falling asleep. Too sad for me. Any suggestions to help her sleep better? Thank you!!