Using two flow sensors connected to one Arduino.

Using Arduino Sensors
6

Why you Attach two interupt pin to the same Function ( pulseCounter() ) ?
SensorPinA have to always increase the counter, and
SensorPinB have to alwayas decrease the counter.

I did it using PinChangeInt Library,
but here is the basic operation using attachInterupt

long lastMillis=0;
long curMillis=0;
int RptInterval=1000 ; 

int SensorPinFwd = 2;
int SensorPinRtr = 3;
int FlowClick = 0;

void setup(){
    
    pinMode(SensorPinFwd, INPUT);
    pinMode(SensorPinRtr, INPUT);


    attachInterrupt(SensorPinFwd, FuncFlowFwd, FALLING);
    attachInterrupt(SensorPinRtr, FuncFlowRtr, FALLING);

    lastMillis=millis();
    curMillis=lastMillis;

    /*
    And do other setup for serial and LCD here
    */
}

void loop(){
    curMillis = millis();
    if (curMillis-lastMillis >RptInterval) {
        doReport;
        lastMillis = curMillis;
    }
    
}

void FuncFlowFwd(){
    FlowClick=FlowClick+1;
}
void FuncFlowRtr(){
    FlowClick=FlowClick-1;
}
void doReport(){
    /*
    Do any calculation and report/display here
    */
}