I worked 3 hours last night, got 3-4 calls. worked on putting in a hard wood floor and got paid $12 for one hour $10 for the other 2 because of guarantees. all you need is a PC (which you appear to have and a phone line)
WORK overnights while your mom is home. YES it sucks but that is what you do.
IF you are not married and You do not live together, THEY can not include his income, only child support. Go to the local WIC or Health and human service office for more details on what they can help you with. THEY will however count your mom's money because she lives there.
You want your son, then this is part of taking care of him. Not just sitting with him, but also leaving him to work to feed him. sorry but if you can't handle it then it would be best for the child to live with dad.
2nd jobs do not usually count in child support calculations. any descent lawyer can get them thrown out. If you think your child support is too low then file for an andjustment. They are normal filed free for the custodial parent.