What would you do? Sleep question?

My daughter is 5 1/2 months old. She is sleeping in her crib...well sort of . The problem is getting her to sleep on her own. We do a bedtime routine, bath, lotion, nursing, lullaby, bed. We lay her down w/her pacifer and she often wakes within 20-30 min. We wait 5 min then go back and comfort her but not pick her up and give her pacifer back. This goes on several times. She then starts crying uncontrollably and no soothing will work. I know she's tired and she barely opens her eyes but she's screaming. Eventually I pick her up...I'm talking an hour and a half after we've been trying to soothe without picking her up. How can the ferber method work if the baby never calms down after those 5min. Advice?