My DD is 19 weeks old. She's always been a good sleeper, co-slept from day 1, and now she is sleeping in her cot. We now have our evenings back as she sleeps from 7 - 11 then we feed her and then she goes down again but for only 4 hours then she comes into the bed with me and then sleeps for 2 - 3 hours. How do I get her to sleep longer, or am I wishing for the impossible? She is part bf part formula fed. The formula feeds are the 7pm and 11pm feeds. Any advice appreciated.