I can understand your problem. Most babies develop a sleep rhythm like grown ups by this age but some do not. They may require some more time. While it can be very taxing for the parents, it is nothing abnormal. Do continue your efforts to bring her sleeping time earlier on.
What might help is avoiding putting her to sleep in the evenings, giving a feed at night around 10.30 or so and then putting her in a quiet room with lights off. Avoid too much stimulation at night in form of playing, television, etc. She can quite safely be made to wear a diaper at night. This would save the trouble of cleaning her up and changing her clothes repeatedly which would also disturb the child. Also, she should now be made accustomed to sleep in a baby cot with side railings. These are quite baby safe. Some toys can be kept in the crib, may be tied up with a string which she can reach with her hands/ feet. This way you shall be able to catch some sleep while the baby, in absence of other external stimuli, shall go off to sleep herself may be after playing for a while.
This habit formation may take some time but can be done. This phase shall pass soon. Enjoy it!