Not rolling over or sitting up

Samantha

My boy will be 7 months on June 2nd and he is not rolling over or sitting up. He has mild torticullis (stiff neck) but it's basically cleared up. Were going to physical therapy for it but they are focusing more on rolling over and sitting up. Hes rocking a helmet. Hes also 25lbs so a lot to move and support. I just feel like a failure 😔

This is my sweet Hunter during a helmet break