Standing and balance

I see a these babies on here crawling and pulling up so well and balancing. My girl is no where near this stuff. She is just starting to move forward when trying the crawl. She isn't really crawling just kinda inch worming. She is trying to pull up but can't really get the hang of it. She had NO balance. And she is trying to go from tummy to the sitting position but can't get that either. I just feel like she is so far behind these other kids. Anyone else baby not doing any of this stuff yet?