It's hard to be a little kid - hard to be a mom, too, right? But ironically one of the ways we can make our own lives easier is actually by looking for ways to make our kids' lives easier - making it easier for them to do the things they want to do.
It sounds a little crazy, doesn't it? But think of how much time and energy you're spending fighting against what your kid wants, trying to explain why not, trying to deal with the fallout when you say no - it's a lot! I have two strong-willed kids so I remember how much work that was. Figuring out how to go with their flow and say yes as much as possible made a lot of things easier.
It also sounds like you have a lot on your plate right now, and that's frustrating for you and your child. New babies make for big changes and that can be hard on older kids. And dealing with big medical issues complicates the heck out of everything. As stressed out as you feel, realize that your 2yo is every bit as stressed - and she doesn't have any grown-up coping strategies for dealing with that. It's only natural for her to fall apart now and then. So try not to take that personally! One trick for doing that is by changing the words you use - get "tantrum" out of your mental vocabulary. Your kid is having a hard time. She's falling apart. She's melting down. That's hard, but it doesn't have the kind of... moral disdain as the word tantrum. She's just a baby having a good cry. As a mom, that can hurt your heart, but it doesn't mean you failed, and it's not something you necessarily need to fix.
Instead of trying to get her to calm down, it helps to focus on two things; prevention, and being calm, yourself, in the moment. Be the calm you want to see. It may not get her to calm down faster, but it doesn't add to the drama and make things worse. Plus, working on being calm is good for you. You don't need to be any more stressed! I can't say what kind of strategy will work for you in that regard - breathing or visualization are common - but it's something to think about in calm moments: what helps you calm down?
In terms of prevention, your story with the water feature suggests to me that you've got a kid who has a really strong focus. That's great! She knows what she wants and knows how to dive in deep when exploring. Of course, that also means it's hard for her to stop before she's done - that's not necessarily a bad thing, although it can be frustrating until you learn to adapt to it. My daughter likes to do things for looooong periods of time, and one of the things it helped me to learn, early on, was how to set her up to have as much time as she needed, as often as possible. This is one of the advantages of home/unschooling! You can give kids time to dive in deep without breaking up their days into a million pieces. But there can be a bit of a learning curve on your part while you figure out how to do that. Go easy on yourself - you're learning too!
So, using the water feature example and 20/20 hindsight, here are some things to consider for the future.
- Plan to spend as long as your kid needs. Obviously with two kids that's harder, and little things like the sun going down can be inconvenient. It gets easier with practice.
- If you know you can't spend as long as your kid needs, plan to go back.
- Bring stuff. Stuff for you so you don't get bored, stuff for the other kid so she doesn't get bored, stuff to eat and drink. Think about how you can transport more stuff. We used a stroller for years, even though Mo rarely rode in it, to transport stuff. I also looked for places where I could park a car nearby, so we had All The Stuff. Heck, for awhile I didn't go to the store without a book in my bag, just in case Mo got Really Interested in something and a half hour trip to buy milk and paper products took two hours. Maybe your kid won't be that focused, but you get the idea. Plan ahead.
- Remember that transitions are hard. Making them easier kind of depends on your child, and that will take some trial and error, but sometimes they're just hard! If you see your child's tears as her statement of how hard the moment is, rather than a "tantrum" it can be less stressful all around. She's just communicating! And yeah, as moms none of us like to hear that our kids are unhappy, but it's still important to hear it. She's having a hard time. Okay.
If you're thinking in terms of a little kid having a hard time, and how to help their life be easier, then it's worth asking why you'd separate her from you when she's upset. There are some good reasons to do that! If you can't find your own calm, then it can be better for everyone to create some separation. If your kid can't calm down with another person in her space - and my daughter was like that - it can be kind and helpful to give them enough space to find their own calm again. But putting a child off can also feel like a kind of punishment, which you don't want - it sure doesn't help anyone to learn to deal with big, uncomfortable feelings when they're being punished for having them! So it's a good idea to work on your own discomfort, so that you can be there when your child needs her mommy.