Moms in a relationship no with the father of your kids!

So I am 21 years old, I have a son he is 2 1/2, me and his dad aren't together because he cheated on while I was pregnant (long story) anyway, I started dating this guy 7 months ago, he is 27, we just moved in together so he could help me with half rent since I pay for everything of my son his dad does not help me ,,. Anyway for you woman that are in a relationship like this How much does your bf help you with your kids that aren't his? Sometimes I get so irritated because I obviously have to afford everything for me and my child and he doesn't really help me, but I also know that it isn't his responsibility so I should t expect his hel economically any advice???? Thanks !!!