Why do stay-at-home-Moms get less social security thanIllegal aliens?

I was a stay-at-home-Mom while I raised 4 kids. I then worked but didn't make much money. I draw less than 600.00 per month social security. I hear that people that have never paid into the system are drawing a whole lot mor than me. What's the story? AND is there any organization out there that has members that are in the same situation as me?