sleep help (very long)

I was looking for info about ds2 and his dependence on me (and I on him!), when I stumbled upon attachment parenting.  As it turns out, I find that my style of parenting follows many of the concepts of AP, without really meaning to, it just sort of works out that way!  That being said, we in a bit of a pickle, and I'm looking for some advice.  I've ordered Dr. Sears books, but in the meantime, am hoping to get some positive insight!

With DS1, I bedshared with him until he was STTN and big enough to bring into the bed with DH (who is a very heavy sleeper).  We then seamless transitioned him to his own bed around 1.5 years. He was so ready for his own space, and actually started to sleep longer in his own bed.  Everything had been going well it seems until I got pg, back in March.  At this point, DS1 was almost 3 years old.  It started with the occasional night here and there, and eventually led to every night of DS coming in our bed at some point in the night and sleeping with us.  I figured he needed some security, maybe he was having nightmares, etc and loved getting some extra cuddles in!

That slowly but surely turned into DS1 needing to be in our bed in order to sleep (which sucks bc he needs more than 8 hrs of sleep and he doesnt nap).  So while I was PG, DH would go to bed early and I would sleep a little later, and this worked for us.  HOWEVER, now that DS2 is here, I do not feel comfortable with my 3.5 year old in bed with my baby.  I had planned to have DS2 in a cosleeper next to our bed, but he also likes being in the bed.  

So now, what we've been doing is DH and DS1 sleep in our bed, and DS2 and I sleep in DS1's bed.  This is working wonderfully for now.  There are a few things I would like to change by the time I go back to work, and I'm not sure where to begin!

1.  I would like to be able to sleep in my bed again

2.  I would like to transition DS2 to the cosleeper in our room when he's ready

3.  I would really like it if DS1 could sleep in his bed.  Hes not able to sleep unless one of us is with him, and its becoming problematic bc he stays up way too late (sometimes 11:30) and he can't sleep without us.  DH gets up for work really early (4 am) and then DS1 struggles the rest of the morning, and its obviously stressful for him.  Now that I think about it, it would be great if DS1 could stay in bed with us, if he was able to sleep on his own there.

I will be going back to work in March, so I have some time, but something needs to change.  I just want DS1 to be able to sleep comfortably for 10 hours without it upsetting him

Thoughts, ideas, opinions? Thank you!