Looking for opinions from other Nannies *Apologies for this being so long*

I am a nanny working in Woburn MA, I currently work 8-5 Monday-Friday, I do not complain when they walk in 15-20mins late I don't even as for compensation (I understand there are factors such as traffic and weather etc.) I started off Nanning for twin 14 month olds in February of 2010 at $720 a week; they had a 3rd baby in February of 2011 and raised me to $800 a week. I am responsible for the fallowing-
*The Laundry Of all 3 children (Washing Folding and putting away 3xs per-week)
*Getting all 3 children dressed in the morning
*Cooking the Children 2 Meals a day (breakfast & Lunch)
*cleaning up after the children’s meals
*Changing all 3 children’s sheets every 2 weeks and washing them
*emptying the dish washer
*plus cleaning up whatever I find left over (old bottles, diapers left in the babies room, leftover food on the high chair etc.)

I have made this family my first priority in the fallowing ways
*being willing to stay a half-hour to and couple hours late on 15 minutes to a half hours’ notice
*Often cancelling things in my own life to cover the needs of their family
*being willing to stay late or come in early with less than a weeks’ notice
*staying late due to traffic or weather complications
*Dropping my huge network of babysitting families to be readily available should they need me.
And the list goes on and on

I have been in childcare since 1999 starting volunteering in a summer school program 5 years in a teaching setting as a certified infant-toddler pre-school teacher and going on 3 years of full time nanny experience

recently I baby sat for the family on a Saturday they had originally asked for 4:30PM-10:30PM Then on Friday changed to 4:00PM-10:30PM at 10:15PM "I received a text message from them we just ordered dinner we might be home really late hope this is ok." They came home at 11:45PM then today he says "I was really disappointed to see that the tub toys where still in the tub (I didn't put them away because they were still soaked and I don't want them to get moldy) and there were a few toys still out on the couch. You had almost 4 hours to clean the house after the girls where in bed." after the children where in bed I still had to clean up all the items used for cooking them dinner, their plates silver wear, scrub down the table and high chair sweep the floor etc. etc.

The twins will be starting pre-school the end of next week (3 days a week/ 9 hours a week)

Today he asked if I would mind changing my hours (7-5 Mon, Wed, Fri and 8-5 Tues and Thurs) - no mention of compensation changes nothing) He also said I would expect that in this 9 hours where you only have one child you can be more prompt with the cleaning and also include more infant based activates in the time that you only have the baby.

I feel Like I am getting walked all over and I just cave and would really like some opinions from other nannies and to just as this says start a discussion about these opinions.

*I apologize that this is so long and thank you in advance for you responses*