I think some people have been very hard on the OP and considering there is just the one post, a hell of a lot of words have been put in to her mouth and a lot of judgements have been made. I'm guessing from the lack of any reply from her, it looks as though she may have been scared off.
Yes their situation isn't ideal and no having a baby at this time probably wasn't great planning, but maybe it wasn't planned, sometimes accidents happen!
We don't know whether the OP's DD is her DP's child or whether the baby was planned. For all we know, this lady could have been a single mum and fell pregnant to her boyfriend and is just trying to deal with all the changes.
She is struggling and she's come here for support and a bit of a rant and was just given a load of abuse. Well done.
Please just bear in mind that for some women pregnancy is bloody hard. I know for me, I really struggled with step parenting in my last pregnancy. My hormones were all over the place, I was knackered, I was stressed and worried about our lack of money and lack of living space. I constantly felt sick for the whole 41 weeks, I was in so much pain with SPD and I was struggling to just cope with daily life and so then when you threw 2 DSC in to the mix I felt like it was just too much to cope with. I went from being totally in love with them to dreading them coming in the space of a few months.
I'm currently pregnant again but coping with things much better this time, our situation is better now though, I'm not so worried about money and we're now living in a bigger house where all the children have their own space, even if it is just a bunk bed.
And for what it's worth I don't see much wrong with an 11 yo boy and a 6 yo girl sharing a room, I mean what do u think is actually going to happen? If they were full siblings would you see a problem with it?
It would be nice for DSS to have his own room but that's not possible, the next best thing would be to make an effort to make him his own space.
If DSS doesn't want a bunk in DD's room then maybe a sofa bed or an air bed in the lounge for OP and he DH to sleep on or let DSS stay up late (he is 11 after all) and he has sofa bed/air bed, at least then he won't be getting moved from one room to another.
This situation isn't ideal but it's just a case of making the best of what you have.
I also think the problem with sleeping arrangements is her DH's responsibility to resolve. Why's it always the stepmum who gets the blame and is made to feel responsible for anything which is wrong?