IBR monthly payment after getting married and having a newborn

Like so many people, I was in SAVE limbo and none of my payments were counting towards PSLF. I know that they say we can buy back but I have no trust in the government right now. Therefore, I decided to switch out of SAVE into IBR last September 2025.

My monthly payment jumped to $3200 / month, which I have been paying for the last 6 months.

I got married last year and filed jointly for 2025, and I have a baby coming this year. Therefore, I was hoping my married filing jointly status + newborn would bring my monthly payment down. However, IBR is estimating my new monthly payment will INCREASE to $3600+ /month. I called both Student Aid and Mohela, and they both confirmed that is the correct estimate for this year. How is that possible? With the new baby coming, I am very worried about how I can make this payment..

Of note, my wife doesn’t have any loans and only works part time. I made ~300k in 2025, which is slightly more than in 2024, when I was still single. My wife made around 30k last year.

My question is, how can my monthly payment increase after getting married with a low income spouse and now with a newborn coming? Am I doing something wrong with the application? I’m very worried as my wife will likely stop working this year to take care of the newborn and don’t know how I can afford to pay my student loans. Any suggestions are appreciated 🙏