Advice about bills and SO

What would yall do if your SO(unmarried) of 4years was living with you. He gives me money each month for bills. He will give like 400$ when the total monthly bills are about 2500$. He knows how much all the bills are. I do ask if he can contribute more. He always says yes but never does. I usually have to hound him only to get like 300more…. He is a capable of giving more. I do work. I’m in lpn. But im in school to be a RN so im only working part time, not to mention we have a10month old son old and I miss work alot because of no sitters or family close… i need advice🥲