Problems with iMessage and switching to Android

I recently picked up a Nexus 5, and iMessage is giving me tons of headaches switching over.

First off, here's a little bit of background. I did not consider the iMessage problem prior to swapping out my SIM. It wasn't until after I was using the Nexus and not receiving messages that I started researching and realized what the problem was. At that point I tried the two most suggested methods I found, turn off iMessages on my iPhone and reset my Apple ID password. Neither had any impact. After that I found a couple other suggestions, such as removing my iPhone from my list of registered devices with Apple and removing it from Find my Device in iCloud. Again, no impact from either method.

After that I decided to call Apple support. They basically told me that from they're end my phone number is no longer in the iMessage system and have no idea why my texts from people with iPhones are still being routed to iMessage.

So now I'm at pretty much a loss what to do next. At this point it's looking like my only option may be to change my number if I want to receive texts from people with iPhones. Does anyone have any experience with this or advice on what to do?