Hey ansonlka,
You did a great job going through the steps to contact your wireless carrier. Typically, cellular network issues comes from your carrier. Did they do anything to help you or send you a replacement SIM card by any chance? We recommend that you try the steps from this article and see if it helps: If you see No Service, Searching, or SOS on your iPhone or iPad
Be sure to also apply the steps to check for Carrier Settings update from the article.
Factory resetting the device should be the last resort and we recommend that you back up your data if you plan on performing the reset: How to factory reset your iPhone, iPad, or iPod touch
Cheers!