I've looked after a couple of babies with similar problems in NICU.
WARNING: I'm going to be quite blunt here, so don't read it if you don't want to. It's difficult reading but I didn't want to leave the post without giving you the option to hear it.
The chest size is the biggest problem. I'm sure they've explained but inutero the baby relies on the placenta for oxygen, but as soon as they are born the lungs have to expand well enough to get oxygen to the heart and brain.
If the chest space is too small, the lungs can't develop and are unfortunately unable to work at birth. In that scenario, the neonatal team try and resuscitate at birth for 20-40minutes, trying to expand the lungs by intubating and possibly chest compressions, and then would explain that they can't survive. This would be a big team of doctors and nurses, it will look very dramatic like on ER and its scary. They would take the tubes and wires away, wrap babu in a blanket and give them to you for cuddles for as long as you wanted. We always offer photos and memory making.
Next scenario is that baby can survive initially but needs to go to ICU on the ventilator. They will do chest xrays and monitor how well his body can cope with reduced lung size. This can go either way. They could cope for a day or two or even weeks or months, but eventually it's accepted that the baby will never be able to manage by himself.
Next is that the baby needs short term support but can breathe for him or herself. They will have long term follow up by a specialist paediatric respiratory team. They still may have longer term problems, such as needing to go to hospital for chest problems with a cold.
Then theres always the babies that can cope better than anyone expects. They are rare little miracles but its not unheard of.
This is all just the lungs side.
If baby has long bone and rib shortening, its possible they have a problem with the growth plates at the ends of the bones, therefore they will never grow past a certain (very small) size. My last patient with this survived for a couple of months, didn't ever grow and eventually sadly died of a chest infection.
Nobody can tell you what is right for you. Either way this is going to be hard and I am so sorry this is happening.
Thinking of you xx