I know you are hearing what's said very negatively, but it isn't all intended that way.
Women are generally socialised to think about everyone else. So all day it's about the school run, feeding people, shopping for people, fetching people, bathing people, cuddling people.
There's a joke about women who want to change their name because it feels like 'Mum, Mum, Mum!' All day long .
There's loads of multi tasking. Even when another parent is pulling their weight, it's unusual for women not to be worrying about everything and everyone or at least bearing them in mind.
Women usually know the name of the teacher, head and class assistant, best friends, best frenemy, husband's boss/bestie/frenemy. Men often know none of the above.
Women therefore find they run out of energy to think about themselves and just be them.
If you did regularly did the dinner and bedtime routine while she had a couple of hours at the gym or having a bath- without interruption- she might find her calm again and be ready to look outwards when the 9pm slot arrives.
If you play your cards right and work with her, as the children become less needy she'll have more time for herself. And time for herself is likely to allow time for you too.
Re the sex thing- having sex because your partner wants it can be really damaging. It's ok if she's definitely enjoying it, enjoying the cuddles and closeness but still with a preference for speed. But not if she's lying there feeling like she's ticked something off the list. Just check she's engaged and with you rather than switched off and writing a shopping list.
Time isn't the be all and end all. DH used to take ages over it all and I lost interest- I literally got bored and couldn't keep up the attention span. I wanted a bit of speed and excitement, but he didn't like that 🤣. He wasn't great at reading where my body was, he just messed about with it prodding things and tweaking things and generally being annoying.
I'm trying to say, what matters is how she responds and feels, not whether you are using all the 'top ten moves to turn her on' that you read in a lads' mag.
Paying attention to how she feels is so important.
It's a two way thing, but you are the one who is asking!