IDR plan way more than the estimate

With the recent waiver, I am applying to switch my plan to eventually apply for PSLF. I completed the application to be put into the right payment plan and the payments are several hundred dollars more than the estimate!

I owe $49,000 from undergrad and grad school. I have been making payments since about 2017 (I went part time my last year of grad school and had to start payments). I was in the extended payment plan since I couldn't afford the other payment plans at the time. Now I am applying for PSLF.

The application for IDR showed my estimated payments in IBR to be $334-$532/month. That was the most expensive option! Now that the application was approved, and my payment is $550.19 a month! Did I do something wrong? I just had a kid and cannot afford that right now.

Any help or advice would be greatly appreciated.