My daughter is almost five months old and extremely dependent on my wife and I both going to sleep and staying asleep. She sleeps in the bed with us most of the night feeding, if my wife rolls over or shifts she will wake up, and if not fed after a few minutes will begin crying which will escalate to screaming. At nap time we have to hold her if we put her down when she is tired she will begin screaming immediately and will do so for at least an hour (we haven't left her for much more then that). If we wait for her to fall asleep and put her down she will wake up before she even touches the mattress and will begin screaming. This is true of bedtime and naptime. Since we started trying to get her to sleep on her own she has essentially stopped getting any sleep during the day and would probably not sleep at night if we were not still keeping her in the bed with us.
I could go on for hours about this, but ultimately, you need to come to your own idea of how you want to implement sleep training. Not one method may work, and none of the methods may work! Sometimes you just do what works for you. Every child is different, so just be patient and I promise that this stage won't last forever.
My personal views is that you wait until your daughter is ready. I tried sleep training my son at 6 months, which was a huge waste of time and stress. A few months later, things just worked. If you can, I would suggest trying to at least get her to sleep in some sort of bassinet for night time.