Not a parent and can't help much but I do understand you pain.

I've moved every few years for the last 15 years and just downsized a two-bed to a one-bed apartment. The result...there is too much stuff in it. As I was packing I felt the same resentment and hate towards all the things that just kept filling up more and more boxes. As much as I don't like it, I've tried to hang onto that hate and it is fuel for the process now as I'm working to reduce my junk to fit a smaller space.

The process is hard, as selling in person or online is surprisingly hard work (I'm introverted and time poor right now). I'm only doing it for the big-ticket items to spare my sanity. The rest is being donated or as a last resort trashed. It is painful to see the money that was sunk into those items literally being thrown or given away and to consider the unnecessary waste but I'm using the experience as a learning moment and as hard as it is I'm being sure to fully experience the pain of fiscal loss and poor environmental stewardship on my part. It will help make me even more thoughtful before future purchases.

I live in the U.S. and rent prices are climbing at an unsustainable rate with frankly unscrupulous behavior by some (corporate) landlords to squeeze every last cent form you. Combine that with other cost-of-living increases and it seems we are headed into an era of having to move frequently just to be able to afford a roof over our heads. It is motivation for me to live lightly to make the increasingly frequent event as painless as possible.

Get rid of everything you can! Books can be checked out from the library, and records probably don’t get listened to (if you use them, maybe keep the most used ones?).

It won’t help you today, but in my closet I chose a pair of shorts I don’t wear anymore and put them in the furthest right spot. Any article of clothing I wore and washed got placed directly to the right of the shorts. After a year (all 4 seasons) anything still on the left side of the shorts got thrown out or donated. It was a surprising amount of clothes.

Everything is replaceable, so give yourself a little leeway and while you’re hating your belongings trim down what you can. If you HAVE to replace something later, at least you tossed out dozens of other items that you otherwise wouldn’t have if you didn’t do this!

I try my best to avoid buying anything new. Donate or resell stuff instead of throwing it away.

Avoid knick knacks and collectibles. No one needs 200 snow globes or whatever.

Can relate! I tried to sell and gift/donate but for my own sanity I’ve also trashed some stuff, even if I absolutely hate trashing things that aren’t broken… and now I have to start over because my mom died and I’m her only child, I had to move all her stuff to my garage and it’s very painful going through her life belongings

Not judging or anything, but this is one of the many reasons why I'd never have kids. A lot of people just have kids because they're on autopilot in their lives, and then all of a sudden they realize it's completely incompatible with their lifestyle. I think that contributes to the popularity of being child free within minimalist circles. I grew up with younger siblings and can remember moving with them a few times, and the physical volume of stuff that such a tiny human needs is crazy, as is the immense marketing pressure on parents to buy stupid shit. It's super predatory to see companies pressure parents into buying the most expensive car seat because otherwise their baby won't be as safe. They can fuck off. Imagine gatekeeping safety, real or imagined, based so directly on money.

I'm not a parent but I can imagine how difficult and chaotic life can be in this situation but as a general tip you can try repurposing stuff or buying multifunctional things. Like currently I'm trying to build a new bed out of storage cubes that can later also be assembled into a shelf.