Girlfriend doesn’t get my imessages but i get hers

For almost a year, my girlfriend has been unable to receive my iMessages. She texts me from her ipad and it doesn’t have a number. i can receive them and respond on my macbook and ipad, but i cannot respond on my phone. I’ve tried deleting her contact, turning imessage off and on, and a bunch of other fixes that didn’t work. I’m not blocked and when i get her notifications, i get a message icon instead of her profile picture. any help would be greatly appreciated.