Cancel the data plan and remove cell phones you can't afford from children. If you need them to have one give them a prepaid. They don't need smart phones and you can't afford them or you wouldn't be complaining about paying rent. Reduce to one car since you have combined payments and if reduce your car insurance coverage after you pay off the car you keep. Don't allow children to get drivers licenses until they can pay for their own insurance.
That's a big phone bill, cut back on that. If money's really tight, see if you can live in a place where you don't need the car - if you only need one on occasion, it's cheaper to rent.
The first thing you need to do is get rid of that expensive cell phone bill.
this bill organizer app should help. Worked well for me http://adf.ly/sChAI