6 months & not sitting

This is honestly probably my fault. I havent really practiced sitting with my 6 month old. Weve done prop sitting since 5 months, but not very often because I had heard from people on the science based parenting sub reddit that making a baby sit can cause delays in other skills & Ive just read about how isnt good for their lower back so we just did a lot of tummy time & sometimes prop sitting.

Now my mom keeps worrying me about him not being able to sit on his own yet. Hes army crawling & rolling both ways but no sitting yet. Is this okay?