Paranoid FTM here!
I'm obviously not looking for medical advice, I'm just hoping that someone can help curb my anxiety 
DD is 19 weeks old. She's a happy, alert and laughs a lot. She sleeps through the night and only seems to cry when she's tired/hungry/wet nappy.
I'm just worried that she's not rolling? She does a lot of tummy time and just seems to lift her head and ... shuffle? More interested in getting the mat in her mouth. I've read that they're meant to be rolling from back to front/front to back and I'm getting nothing here.
Saying that, she likes putting weight on her legs and likes to be 'stood up' a lot.
She's a good size baby, 16lb.
Can someone please tell me that I'm worrying over nothing?