Not sitting at 7.5 months

I’m a little concerned about my daughter’s physical milestones. She seems to be meeting others, she babbles, has two teeth etc etc. but she cannot sit. She has trouble even sitting assisted with the boppy. She also shows no interest in crawling. She basically lays on her back or tummy with some rolling. It’s like she hasn’t progressed physically in months. She’s a happy little girl, but I am most concerned about not being able to sit at all. We cancelled her 6 month dr appt due to covid. She now has her 6 month appt at the end of this month. Unless I cancel again. I’m in MA and it’s a real hot spot still.

This might be a real stretch, but she had a really bad umbilical hernia. The dr was talking surgery. It has gone down considerably in the past few months, but it’s still there. I can’t help but wonder if that means her abdominals are not strong enough to assisted her with sitting. She also has a sacral dimple and her bum crack goes up higher than normal. I wonder if that causes any issues?? 🤷🏼‍♀️🤷🏼‍♀️🤷🏼‍♀️. I’ll be talking with her dr, but it could be in 20 days from now or end of June if I cancel the May appt.