I need advice!

We are co-sleeping and we had a really good bedtime routine that worked for all of us. DD used to take 3 naps, DS one. At bedtime I did bathroom routine, story, lights out, prayer, song with DS. Then I left him, he fell asleep on his own, I nursed the baby to sleep and tucked her in, about an hour later I joined them and another hour later DH joined us. DD is now 13 month old and two weeks ago she dropped 2 of 3 naps. I like that now both children nap at the same time for about 2 hours and I can get a lot done around the house. BUT bedtime isn't working at all. DD wants to sleep two hours earlier and that shakes everything up... We tried the following:

1) DD to bed when she wants to, DS to bed at his usual time. He wasn't quiet enough and woke his sister up, she screamed for 3 hours. No one slept.

2) DD to bed when she wants to, and DS to bed before her. DS screamed for 30 minutes because he didn't want to go that early... no one slept.

3) DD to bed when she wants to, let DS sleep somewhere else. As soon as the lights go out he wants to go to “the big bed”. When we wouldn't let him he started screaming and screaming...and woke everyone up.

4) DS to bed as usual, DD sleeps somewhere else. DD nurses quite a lot during the night, when I'm not there she wakes up and won't go back to sleep for hours. When I'm with her and DS wakes up and I'm not there he starts screaming and wakes everyone up. When I try to be there for both I'm not getting any sleep and staring on the monitors all night...

5) DD to bed when she wants to, DS at bedtime into the car or stroller, drive him around till he falls asleep, then put him in bed. That works. But that's no solution....

Please help me. I'm so tired.... I don't know how to fix this.