You need more money? Ask, they say no? make sure that every time you talk about money they know you need more money. Every time you do something extra remind them you need more money, they talk about their kids you tell them you want kids but you need more money.
When you interview and they say they pay X you tell them that your expenses are Y and you need X+ W to make that work. You don;t leave any openings you need X + W and god damnit that's it.
If it makes them uncomfortable, good. If they fire you, collect unemployment and do a side job till you get what you NEED. Stop accepting less and they will stop offering it. Or at least they wont be fucking you with your permission.