The terms of your lease should address this very question. if it does not require it, you don't have to have a two bedroom. However, it might be worthwhile to have an attorney go over the contract with you and write a letter to the landlord
The information provided in this answer does not create an attorney-client relationship and is not considered to be legal advice.
Generally speaking, it's a good goal for children to have their own bed. I have seen several custody hearings where that is an important consideration. However, absent a lease or home owners association provision addressing this issue (which would be a unique term), the landlord probably does not have any authority to require you to move for this reason. If you are feeling bullied, it may be a good idea to get an attorney to look over the specifics of your situation to empower you with information.
I hope this answer helps a little. I am happy to answer follow up questions.