Low alternator voltage after changing voltage regulator

The car is getting difficult to start. Have to jump start everyday. The battery is fine, according to O'Reily, but the charging is very slow.

I monitor the voltage while the car is running. The output voltage is around 12.8-13.3 Volts. It never reaches to 14 Volts which it suppose to.

I have replaced a brand new Bosch voltage regulator, Nothing is changed. Still got low alternator voltages.

There is no malfunction lights on, and the battery do charge, but with a very low rate. Also the battery seems running out the juice pretty fast. After 6 days parking with a fully charged battery, the juice runs out and the car won't start.

Does anyone know what the issue is?

Thanks

Low alternator voltage after changing voltage regulator