I become worried when there is a child who younger than my child but can do something that my child can’t do it.

I would be concerned and observe further before blindly panicking. It depends on the individual as well

I think one should first check with the PD if there is an issue and the one should act towards it

Monitor carefully and seek expert advice if you feel baby is not developing on track

Should always check with the doctor as early detection can make a big difference

totally yes, a mum is always worried about everything.

Each child is unique and grow at their own pace...

Would check in w the PD and follow his advice

Then seek help from a medical professional

Intervention at the right time may help