Hey there Kristin10,
It sounds like you are sending iMessages that aren't going out over cellular. I would use these steps to help resolve the issue here from the article named:
iOS: Troubleshooting Messages
- Open Safari and navigate to www.apple.com to verify data connectivity. If a data connection isn't available, troubleshoot cellular data or a Wi-Fi connection.
- iMessage over cellular data might not be available while you're on a call. Only 3G and faster GSM networks support simultaneous data and voice calls. Learn which network your phone supports. If your network doesn't support simultaneous data and voice calls, go to Settings > Wi-Fi and turn Wi-Fi on to use iMessage while you're on a call.
- Restart your device.
- Tap Settings > General > Reset > Reset Network Settings on your iPhone.
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All the best,