Cerebral Palsy scare

My daughter is 21 weeks old. She has reached majority of milestones (minus rolling from tummy to back. She did it a few times then stopped) but rolls from back to tummy perfectly fine (though only rolls on her left side). I was talking to a friend of mine and she said she noticed my daughter sometimes keep her arms/elbows bent and by her head in fists then she said she noticed she also crosses her feet when laying down on me (but doesn’t normally keep them crossed when being picked up)... all of which are signs of Cerebral Palsy. At her 2 month check up, her doc did say she seemed a bit stiff, but nothing to be concerned about yet. Other than that stuff, she seems perfectly normal. She’s reaches and grabs objects, can hold her head up perfectly, pushes off her arms on her tummy, lifts her head when on her back, can pretty much sit up, can put weight on her feet, “talks” like crazy and has started to lift her butt up to start the crawling going. Is there any truth to what my friend said? I’d figure if she had CP, she’d be behind in milestones but she seems pretty ahead. Any advice would be great.

P.S. I should also mention she also said if not CP then maybe a form of mental retardation. I don’t know if I should just get rid of my friend lol or take what she’s saying seriously.