Am I obligated to give maaser if

I was/am going through financial hardships and I promised Hashem that I will give maaser on any and all income that I receive, because it is a required mitzva. I have been keeping my word. My daughter receives disability of $733 and as soon as it is put in my bank account, I go straight to the computer to donate$74 to a Jewish cause, mostly to help poor people in Israel. Here is my problem; doing so leaves me in a position where I cannot afford my rent (700) or my bills. Thankfully, buying food is not a problem because I receive assistance for that. I don't want to break a promise to Hashem; Do you have any advice on what I can do?