Wrong Readings from ACS712 using Arduino Uno

Hi, i'm having problems when sensing voltage from an ACS712 current sensor.

When I connect a load (in this case 30 omh) to the sensor, my multimeter shows a change from 2.52 to 2.78, but the ADC (A0) of the arduino won't detect it. Only a very very sutle change from 2.52 to 2.47, this happens also if a I show the Raw data from the ADC, only a very little change.

The circuit it's pretty simple and also the code too.

Idk what else to do honestly, I already change the DC-DC converter to a Lineal Regulator and the same happens, also change the sensor for a new one, and nothing changes.
Thanks!

#define Sensor A0
float voltajeSensorent;
void setup() 
{
  // put your setup code here, to run once:
  pinMode(Sensor,INPUT);
  Serial.begin(4800);
}

void loop() {
  // put your main code here, to run repeatedly:
   voltajeSensorent = analogRead(Sensor) * (5.0 / 1023.0);
   Serial.print("Entrada:");
   Serial.println(voltajeSensorent);
  delay(500);
}

There are 3 versions of ACS712, 5 Amp, 20 Amp and 30 Amp, which do you have? Check page 5 of the datasheet for sensitivity ( mV / Amp).
https://www.allegromicro.com/~/media/Files/Datasheets/ACS712-Datasheet.ashx