You have my sympathies! I went through the same thing until my son was probably a little over 2, and then he was diagnosed with Type 1 diabetes!
It really *does* mean a sacrifice to parent this way. And our strong marriage definitely showed signs of strain at times!
A couple of suggestions I have for you:
** Consider a sling...many accomodate toddlers. Once he is heavily asleep, you can put the sling down on the floor.
www.hiphmmock.com also has slings specifically for older babies & toddlers...
**You could also think about a pallet upstairs... putting a folded comforter on the floor, with folded towels to prevent him from rolling too far if he is a "thrasher"as my son is! Put some expressed breastmilk on the towels & comforter s he has your "smell" near him to simulate your presence. Being that he is 15 months, I don't think that would pose a risk. Obviously, you wouldn't do that with an infant due to the risk of suffocation.
One other thing you might consider is hooking up with an AP support group, if there is one near you.
www.attachmentparenting.org hs a listing of local groups. Often they will have a babysitting co-op, so you will have like-minded folks to trade off a few hours with!
Let us know what you decide & how it works!