iMessage won't let me use my phone number, stuck on "waiting for activation..."

I had an iphone 6 plus, and i was able to use imessage no problems whatsoever. I recently upgraded to iphone 6s, and everything works fine except for imessage and facetime errors.

I can send sms messages and call people using my phone number, but under settings > messages it has "waiting for activation" error.

I looked on apple support communities and other websites to try to find a solution to my problem, but have not been successful so far. I have

- turned off imessage and restarted my phone, then turned on imessage again

- signed out of my icloud account under imessage settings

- removed my sim and re-inserted it

- checked the date and time settings

- factory reset my 6s and tried to sign into imessage again

after doing all these^ things, nothing has worked.

I read on << http://www.idownloadblog.com/2017/09/19/how-to-fix-waiting-for-activation-issue- in-imessage-and-facetime/ >> to try to get another iphone, reset it and turn on imessage in that phone so that you know it works, then put the sim back into your normal phone and imessage should work. So, i put the sim back into my 6 plus (without restoring it yet) and imessage still wouldn't activate. Then, i restored my 6 plus and tried to set up imessage again and it STILL would not activate or show my number under "send & receive".

the reason i want to activate my imessage is because i text lots of people without actual phone numbers, and barely anyone knows my email.

Anyone have any ideas how to fix this?