I guess there's really no way to keep everybody happy this time. I just hope my parents can understand this.
I know it would be nice if everyone could be made happy, or at least be understanding, but... I'm sorry to say, it just doesn't always happen in real life.
For this vacation, you've made a commitment to house-sit and pet-sit, so I think you have to stick with that. The animals are used to being treated a certain way on a certain schedule; they don't understand they're irritating you and it's not really their fault, so I think you just need to work with them as best you can.
And for the future... I think if you don't want to repeat this experience, you'll just have to say no to your parents. It won't be easy and they won't be happy, and they'll probably try to pull guilt cards and talk about how much you "owe" them and so forth. It will not be a fun time. But I think you either have to do this, and free yourself from the obligation of house- and pet-sitting; or you can continue to accept the obligation, but find a way to make it work better for you.
Depending on the times and distances you might be able to commute instead of staying over, or host a friend at night instead of DF if he needs more sleep to work, or something like that. I'm guessing your parents don't pay you for doing this; but would it be possible, and worth it to you, to pay someone else
to do the sitting, or at least help you out? That's an extreme way to avoid confronting your parents, but it might work for you, since the current arrangement seems untenable.