Uk mums! Housing advice?

I currently live in a ONE bedroom ground floor flat. There is myself, also my partner, 20 month old daughter and 7 week old baby boy. I have been promised a 3 bedroom house once he is born. Obviously now he is 7 weeks old.

I have been declined my medical form because it's not at satisfactory yet I've had a severe brain injury, with brain surgery. I had to learn to walk and talk again with life long issues. My partner also has osteoarthritis.

Im having to sleep on my sofa with my newborn ( in his bedside cot). We have no room for a bed for our daughter or son in our bedroom.

Im in band D in housing, yet band B is overcrowded and that's what I should be in. At the moment I can only bid for two bedroom property, mostly flats. But the issue is I'm so far away on banding that I'm coming 450 in position for housing because my banding isn't correct. Something has gone wrong, nobody with 4 people should be allowed to live in this condition. We aren't sleeping at night, both babies wake eachother up etc. baby is freezing bevause we are in the living roomZ

Does anyone have advice regarding this?? Or am I expecting too much??