I have times when I have felt like this. I have a disabled child who cannot attend school so I lost my whole life to caring and it's almost broken me. A few years in and my oldest two have more independence. I refuse to pick up after them so if they leave toys everywhere I give a warning then it all gone in "toy time out" and they have to earn it back. I expect them to scrape their plate and put it in the dishwasher (needs constant reminders but they do it). Kids can change their own beds. Ironing isn't important. Basically I delegate as much as is reasonable to the children, it doesn't fix it but I feel less of a maid.
One trick is get a new game or craft activity on a weekend and give it to them Saturday morning then you sit and drink tea and half supervise but still getting your own time. I got my old wii console out for mine recently and they play for a good couple hours at a time working together on all the Lego games, I sit and watch and scroll mums-net.
You have probably had the batch cooking advice? I batch cook bolognese, curry, stew- all foods that I defrost and microwave then just cook the accompanying pasta or rice etc. Sometimes I do a Shepards pie of something to freeze but they take up a lot of room and when feeding lots of people they do t go as far for the space in the freezer.
Do you have mum friends? I've never had success but I've always been recommended doing play dates so you can give each other time off. You should look into getting a babysitter and finding a hobby to give you something other than work and mother in your life.
With your youngest being 7 I think it's reasonable to tell them one weekend day you are having a sleep in and not to wake you before eh 10am.
Can you find an age appropriate box set to watch with the kids? Or swimming? Try think of something to do together with the kids that YOU would enjoy doing not just facilitating the kids happiness keep yours in mind too. Nurturing time with them you enjoy so parenting doesn't feel quite such a burden.
Do they fight? Is it the mess? Helping with homework? What is it you hate about parenting this age maybe if you are more specific we can give you our tips to make it easier?
I know how you feel. I think it's worse when the other parent is living their life as though they don't have kids. I struggle to hold my toung when my kids make comments about their dad being fun the rare time they see him. Or when parents with support moan about how hard it is but later in the conversation mention something that I could never do as always have the kids. I think unless you parent alone and constantly it's hard to really connect to it. But as you see on this thread lots of us understand the feeling you just don't see it in real life because we would never tell anyone out of shame or fear our kids would get wind of what we said!
What I will say though is think about the relationship you want with your children as adults. Will you want them to fly the nest and you wash your hands of them? Will you want to be an involved grandparent? My mother clearly had a preference for younger children. She worked with little ones and vocally didn't care for parenting me as an older child. She's very good with little ones but fuck am I letting her near my kids to cause the hurt and rejection I felt as a child when I got past the age of 5. Think how quickly your kids have grown for babies to what they are now. You are essentially more than half way through. You just have to make it as enjoyable as possible to make the time pass as fast as the baby years did and then you will be out the other end soon enough.