How much money to ask for my work?

You should charge them for the full time you were working..Since you didn't get any time off for your self , then they should pay you for each hour u worked regardless of the fact that they paid for everything..If you continue to keep babysitting you need a contract laying out exactly what you will work , time off and what u are expected to pay..This saves you from being taken advantage of. Next time require one full day off for every 5 days working.. or 2 days for every 7 days working..