J.H.
We went through that phase too. After many frustrated nights we decided to just let her scream it out. At first we'd go in after 5 mins and calmly tell her it was sleep time. then the next time we'd leave it for 10 mins, go in and tell her it was sleep time she eventually got the idea. It meant a couple of nights where she nearly screamed the house down but on the thrid night she only screamed for five mins and the next night she slept. It's tougher on the parents than it is on them. My daughter is now almost three and I'm less hesitant to let her scream out a tantrum ( which don't last long because she realizes she's not being given any attention) after about a minute of screaming now she comes to me and tells me she's ready to use her normal voice.
Another option may be to think about a toddler bed but perhaps not for a couple of months yet.
Jen