My biggest battery user is phone.app. I talk on the phone a lot for work, but no more than when I got the phone.
The biggest impact on battery in your case will be the cell signal. With a full 5 bars the phone will use a lot less battery when talking on the phone then it will when using 3 bars.
There's a few ways to mitigate that:
1. If you have a poor signal, turn off LTE. A poor LTE signals uses more battery than a poor 3G signal.
2. If you are frequently in areas with Wifi and your carrier supports Wifi calling, then use it as that uses less battery if the cell signal is weak.