Getting married on disability?

I was recently diagnosed with renal failure in November and I am 24 years old. I am doing the Baxter PD Cycler at night. I am on medicare and medicaid. I currently receive SSI but was not entitled to Disability because I did not have enough work credits. Me and fiance have been together for 5 years now and have a 3 year old son. My fiance has enough work credits to receive his benefits if he needed to. My question is this, if we got married, would I be able to use his work credits? I have heard that you can but just would like some actual answers. Also, because I have a 3 year old son and I am disabled, would he receive a check as well? Me and my fiance have always planned to get married but just have put it on hold. Without me being able to work it has just taken a tole on us financially. Any answer will be extremely helpful. Thank you =)