Change of living situation

Hello, 

Me and my ex boyfriend stayed to live together after we broke up (we are not together anymore, but manage to live together because it is hard to find another apartment), since then i have been with the jobcenter. With us, lived also a refugee from Ukraine that now left. The apartment has 2 bedrooms and one living room/kitchen so i was staying on the sofa. now i can finally move to a normal room and have privacy, but this also means i have to ask for the jobcenter to give me more money to pay my half instead of third and i am afraid they will say no, or force me to move out (which is really impossible with the budget i get, if i want to stay inside berlin - and i dont want to lose my contract!). 

i want to ask what are my possibilities. i was unnable to find information what is the maximum the jobcenter can help with rent (right now i am getting warm about 600 eurs and i need at least 800/900 to cover the room costs). it is really hard to live on the sofa and i was able to maintain my sanity only because i believed it was temporarily  - the apartment is not suitable for a 3 people wg (since the kitchen is in the 3rd room). 

in addition i want to ask what happens if my ex moves out suddenly? i know the landlord is under no obligation to not "re evaluate" the contract, so i may lose the apartment since i do not have sufficient income at the moment. I may be able to find someone to still replace my ex in the larger room and pay the majority of the rent, but i still need to cover my half (its a bit more like 60-40 since one room is smaller than the other).

any advice appriciated!!!