Ok, so you are saying that you have logged into FaceTime on your Apple Watch and received a notification from Apple that you are now able to use your phone number with FaceTime on your Apple Watch. Please list the steps here on how you accomplished this.
The OP didn't provide the entire notification nor did they say whether there was an OK, a link or otherwise which is why I asked about it but they did not respond. We don't know what their notification looked like but I believe it best to err on the side of caution.
But I will await your explanation of how you logged into FaceTime on your Watch and received a notification from Apple that specifically said you did this on your Apple Watch.