Will iMessages sent to my iPhone number also be shown on other iPhones sharing the same Apple ID?
The answer to this depends on the settings of your mother's iPhone.

More specifically, on your mother's iPhone:


Go to Settings > Messages
Scroll down to and tap on Send &amp; Receive
Check to see what phone numbers and addresses are listed under You can be reached by iMessage at and ensure that anything you don't want ticked (e.g. Your iPhone number) is ticked
It's probably also a good idea to see what's listed and ticked under Start new conversations from 


In this way you can share the same Apple ID and control what is received on individual devices.

You also have two other options:


Stop sharing the same Apple ID or,
Stop sharing the same Apple ID and use Family Sharing instead to share apps, music etc.


More details about Family Sharing is available here.