Help need...

I've been posting on a few forums last night (both scrapbooking and parenting) about my drama with getting the kids to bed as I am really struggling at the moment. I have been totally blown away with the response from the scrapbooking forums (and disappointed with no response from the parenting forum). I still feel like I don't have any workable solutions though... If anyone reading this has any advice, please please share with me!

Does anyone have any advice re getting kids to go to be and stay in bed?
I have a 3, 2 & 1 year old and due in late april with #4. DS #1 (3) and DD (2) share a room and are horrible to get to bed. DH works shift work (6pm - 6am) and is only home 7 nights a fortnight in 2 or 3 day runs.

DS #1 and DD go to bed at the same time (after a bath), I read 2 stories to each and say good night to them. We now have a light in the bedroom for DD who is scared of the dark at the moment. Eventually DS #1 is going to sleep if you lay there with him, but DD is not sleeping then and will settle anywhere else except her bed.
DD is still having a nap during the day (and needs it) and is getting to overtired at night by the time I am getting DS #1 to sleep. My children also don't sleep in and are awake at 6ish every morning even after late nights.

I've tried time out, ignoring, shutting the door (leads to a very messy room), talking to them, smacking and nothing is really working other than sitting in there, and then it is only working for DS #1. I also have an unstable pelvis whilst pregnant and have trouble getting around so this is adding to the prediciment as well. We did sleep school before DS #2 was born and I was spending an hour a time (including in middle of night whilst breastfeeding) doing the whole routine. After over a month (or two) of trying "the" routine, I gave up. I was exhausted. Much like now really.

I am feeling useless, a failure in terms of mothering re bedtime and in a mess as I need to get this sorted out now before the baby comes along and before DS #2 (1) decides he wants to sleep in a bed and be like his siblings.

Any advice anyone has would be greatly appreciated.
Ros

P.S. I got an e-mail from FK yesterday they accepted a layout of mine (that was from my EDM album). I decided that the EDM comp. wasn't for me as I was struggling with the themes. Will still do the album for my kids as was the intention but it will be "my" way and not "theirs."

P.P.S Drew's latest sentence from yesterday morning is so cute, I have to share!
Nikki is in Drew's rom with the door shut going "knock knock"
Drew opens the door and says "hawoo, how da?" (hello, how are you doing?)