I previously shared an Apple ID with other family members that had other apple devices (another phone and an iPad). At that time, my iMessages were going to their devices also. So I recently created a new Apple ID and assigned it to my phone for iMessage. Is there still a chance my messages are going to the other devices? In my "send/receive" setting of iMessage, it shows my phone number and my personal email address. So, I guess, when I create the new Apple ID, does that phone number now come off the old ID and is only assigned to this new one? Or can it still be on the old one at the same time, meaning they could get my messages?
You will have to go to the other devices and remove your phone number and email address from iMessage. It's always better to check those devices carefully when making a switch to make sure you don't have other cross linking happening.