Can't iMessage texts from iPhones after switching back to Android?

I've been having this problem receiving iMessage texts to my android, and I understand that it is because the iPhone still recognizes my number as an iPhone instead of an android so it's not sending as an SMS… I didn't receive messages from my boyfriend because for two days because iMessage doesn't recognize my phone. I've called ATT to reset my network, restarted my phone, physically deleted his contact and manually put it back in… Nothing. I've tried to deactivate my Apple ID but I've had no luck. It's also not just him, but from other friends who have an iPhone as well. Can someone please help me. I'd really appreciate it.

Added (1). By the way… Sorry for the typo in the title…

I think some setting pblm ll be happnd so check your mobile phone message setting thn it ll be clear.