Anyone else feel like they were a placeholder after everyone around you had kids?

Has anyone else experienced something similar to this?

In the last few years it seems like everyone in my life has had kids except me (by choice). It’s like suddenly I’m disposable and an afterthought with everything, even with my parents (68F/68M) who have been helping out with my nieces who are now 4&6. I am understanding for the most part but I had my wedding 3 years ago and all anyone in my family talks about was how inconvenient it was because we did a wedding away and my sister (42F) got pregnant before it. It was just complaints non-stop to the point I wished I eloped. Even years after the wedding. Meanwhile for my sister‘s wedding, which was massive, but here it was my mom‘s favourite day of her life. Also my mom replaced all the baby/kid photos of me with ones of my nieces and gave me back my baby photos, some of which got damaged from stickers from the photo album she took them out of. It was both weird and hurtful. 

Two years ago we went away for my sister’s 40th bday and this year my sister was telling me she wants us to go on a spa trip with me to celebrate my 40th birthday but when it came to booking it, she was flaky and then last minute she bailed so I ended up booking a last-minute trip to South America with my husband. To celebrate with my family we decide we would get together this weekend and just have a cake and dinner but schedules changed for me because of work but then a couple hours later it changed back (annoying I know), but they had already rescheduled the cake so now we’re doing a random weeknight that might be problematic for me for work, but I won’t know till the last minute.

Also, my best friend (38F) who grew up as an only child and was always a bit self absorbed had a baby and the last 4 years our conversations are 90% about her pregnancy journey, being pregnant, having the baby, oh wow she just started eating carrots blah blah blah.

I get that it’s part of life but I’m just so sick feeling like a placeholder. It’s like my value has gone down and my time is not worth as much as everybody else’s and the people I was close to don’t really seem to care that much because they have other things they care about more now which I get because they have kids. But it still stings and I just feel like what’s the point of anything. It’s probably also it comes from the fact that I feel like my sister was always my parent’s favourite. She a doctor now and I work in the arts and she has more in common with my parents, especially my mom so there’s definitely a bit of distance there. I also got punished a lot more growing up because I had a temper for my sister never got punished because she was always really easy and well behaved. I was the only one that got screamed at and slapped and now my mom is this perfect understand and patient angel to my nieces which I’m happy for but it’s just also odd to see that side of her that I wish I had. 

TL;DR I feel more like a black sheep now that I don’t have kids and everyone else does and it’s brought up some things from my childhood.