My first daughter Matilda went to 1 day sleep around 13 months. She was doing the same thing, sleeping well for the first sleep & then crap all for the second sleep & then would go to sleep late at night. When we cut out the second sleep she did really well and started having her day sleep around 11am (at first, it took us 3-4 months to move that one back until midday), and cut out the night sleep she started going to bed at 6.30pm which we loved.