Constantly put on the spot / stuck in my job

I’ve been with my nanny family since January, and while I really love the kids, I’m starting to feel conflicted about staying. The parents can be great, but at this point, I feel like I might be getting taken advantage of.

The very first time I ever called in sick or requested a day off (it was last-minute, but I wasn’t sick the night before), I got an email saying:

“Moving forward, it’s essential that absences and tardiness be limited strictly to extreme emergency situations as determined by us. If you feel like you can’t commit to that, we will proceed with termination in accordance with section 19 and 20 of our agreement.”

I had a 101+ fever at the time, and their baby was only 9 months old, so I was shocked at how harsh their response was. It really rubbed me the wrong way, but I brushed it off and kept working for them. Since then, though, it’s left a bad taste in my mouth, and I can’t shake the feeling that I’m being taken advantage of.

They ask me every. single. day. if I can come in early or stay late. They call me during my off time to see if I can come in, or they’ll wait until right in the middle of a tantrum to ask me to stay late—when I feel like I have no choice but to say yes. Every Friday, they ask about my weekend plans, and if I mention even a little free time, they beg me to work.

Now, they want to increase my hours even more, and I’m really torn. The dad is on paternity leave until May, and I feel guilty about leaving when I know they’ll need more help. Both parents have intense jobs, and when I accepted the position, I said I was open to increasing my hours when the dad returned to work in May. But after everything that’s happened, I don’t even know if I want to stay.

The problem is, May is creeping up fast, and they’re desperate for more hours and flexibility—which I’m not sure I want to give. On top of that, I have a trip planned with them next weekend, and if I do decide to quit, I feel like I need to wait until after that to avoid any awkwardness.

As I overreacting? Any advice would be really appreciated. I feel super stuck. Like I said - I love the kids and the parents are great bosses when they're great

Edit; I feel terrible for calling out sick day of - but the Dad is off of work and home with the kids until I get there. I figured Dad wouldn't want a sick person in the house