Returning to work

I have a little over 3 weeks left of my maternity leave and I'm starting to get really worried. My baby is colicky and really doesn't like anybody but me, she barely even tolerates her dad. I also work 7 on 7 off nights, so on the days I work I'll be away from her from 8p to 7a and then during the day she'll have to go to daycare so I can sleep at all. I've struggled with ppd and I'm afraid that the stress of returning to work and leaving my baby is only going to make it worse. Unfortunately I work in the medical field so a modified schedule isn't an option and I carry our family insurance so I can't quit either. I just wish there was some way to extend my leave a little longer to let baby mature a little more, I can't stand the thought of her screaming and being miserable all day at daycare.