Should I charge more for babysitting?

So I recently started babysitting for a family member. I watch her three kids and only charge $30/day; everything started great. She drops them off at 7:45 to be at work by eight and picks them up by 5:30 pm except for Tuesdays and Thursdays when she’s busy until around 6. Well, she recently has started to take advantage of my kindness; I feel like and some days doesn’t pick up the kids until after seven or sometimes closer to 8 pm! Mind you; I feed her kids three meals as well as 2-3 snacks a day out of my own pocket. I have two kids of my own and just found out I’m expecting another in Nov., and I am changing diapers on 1 of each of our kids. Am I in the right to feel angry and frustrated? Is it wrong of me to want to charge her more? I was waiting for her to pick up her kids tonight and planning on an early night only for her to message me right before 6nand say she wouldn’t be able to pick up the kids until probably after 8 pm

I would def ask for more money at that point