Help me!! I don't know what to do about my job.

Okay: so first off i'm sorry if this was the wrong category for these questions/ advice seeking but i didn't know exactly where this would fit. I've been working for this family as a nanny for about 4 months. In the job description it stated I was responsible for the 2 year olds care only & only his laundry and his dishes. In the interview I was told the same thing and when the family asked how much I was looking to be paid I said $12-15 hourly (typical for my area). They told me the starting pay was $10 hourly but that if I worked hard I would get a raise. I was very interested in a potential raise so I did everything I was asked and worked extremely hard. On the first day I was asked to do (all) laundry and wash (all) dishes and I did so because I thought if I did it for long enough I would get a raise. Well i've been at it for 4 months now and typically I do a sink full of dishes and about 6 full loads of laundry in a weekend (I only work weekends for the job). I finally grew a pair and talked to my boss about the situation and told her I would like to be paid more for the increased amount of work that I had been doing. She offered me 5$ extra per load of laundry I was doing...but I personally feel as though this isn't enough. Here's why: I haul a 2 year old up the stairs to get each basket of laundry (about 5-6 trips) (the baskets are extremely heavy). I sort all the laundry (1 weeks worth for two adults and one child + towels & sometimes sheets) into the basic categories, wash and dry it, fold it all and put it all away: on hangers/ in specified drawers/etc.. I sometimes have to deal with gross stuff too, like separating underwear from pants. I also always take their change out of their pockets for them and turn things right side out. They have even given me giant black trash bags full of salon towels (they own a salon) for me to wash. So I asked to be paid $8 a load,my boss agreed but seemed hesitant and low key pissed about it haha. I asked her a second time if she was sure that it was a fair cost on her end also and she said that it was fine. So.. another situation occurred today. While I was watching the child, I had just put him to sleep (it takes an hour), my boss's family member dropped his child off for me to watch... I had no idea he was coming.. I had no idea I was going to be watching his child. It made me extremely uncomfortable and angry because I had never agreed to be responsible for another child and at that point I couldn't do anything about it, it's not like I could kick the child out of the house. The child is 10 so he wasn't a tremendous handful; however, he did wake the other child who is 2 up from his nap twice which is extremely frustrating. Also the whole principle behind what happened just really leaves a bad taste in my mouth. When I told my boss about the situation she told me she couldn't tell her family not to come because it would be seen as very rude. She did offer to pay me extra for him being there (how much extra I do not know yet) but she said "If I keep having to pay you for every little thing extra, it's going to make this a very difficult relationship" But i'm really confused as to how I'm being paid for every little thing extra when i've steamed her floors, swept, done 6 loads of laundry, dishes for 3 people and sometimes more, gone shopping for her, helped plan her sons bday party, and numerous other things for no additional pay. So basically these are my questions: 1) Is 8$ for a load too much to ask? 2) What should I do? 3) Am I asking to be paid for every little thing ?