Arduino line follower and sumo robot in one code

I'm trying to make a sumo robot and a line follower robot together.I have written the code, but when I run the code, I have a difficulty doing the drive I have written on Arduino idle.
I use Arduino UNO, breadboard, L239d, 2 DC motors, 9V battery, ultrasonic sensor hc-sr04, 2 qre113 analog, 1 switch on-off and some cables.
Does my code have any problem? How can I add a line follower code in sumo's Arduino code?

//#define E1 10  // Enable Pin for motor 1
//#define E2 11  // Enable Pin for motor 2
 
#define I1  9 // Control pin 1 for motor 1
#define I2 10 // Control pin 2 for motor 1
#define I3 11 // Control pin 1 for motor 2
#define I4 12  // Control pin 2 for motor 2
int QREi1113_Pin0 = 0; //connected to analog 0
int QREi1113_Pin1 = 1; //connected to analog 1
#define trigPin 5
#define echoPin 4

// defines variables
//long duration, distance;

void setup() {
    Serial.begin(9600);
    pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
   pinMode(echoPin, INPUT); // Sets the echoPin as an Input
    
    //pinMode(E1, OUTPUT);
    //pinMode(E2, OUTPUT);
 
    pinMode(I1, OUTPUT);
    pinMode(I2, OUTPUT);
    pinMode(I3, OUTPUT);
    pinMode(I4, OUTPUT);
    
    
}
 
void loop() {
  int QRE_Value = analogRead(QREi1113_Pin0);
Serial.println(QRE_Value);
//int QRE_Value = analogRead(QRE1113_Pin1)
//Serial.println(QRE_Value1);
long duration, distance;
  digitalWrite(trigPin, LOW);  // Added this line
  delayMicroseconds(2); // Added this line
  digitalWrite(trigPin, HIGH);
//  delayMicroseconds(1000); - Removed this line
  delayMicroseconds(2); // Added this line
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) / 29.1;
  
    Serial.print(distance);
    Serial.println(" cm");
ROTATE(); // start roteteint QRE_Serial.print("xroma ");



 if (distance < 10){
    Stop();
    while (distance < 10 ) {
    FORWARD(); 
   
  distance = (duration/2) / 29.1;
  
    Serial.print(distance);
    Serial.println(" cm");
  
    QRE_Value = analogRead(QREi1113_Pin0);
    
    if ( QRE_Value > 150 ) { break;}
     delayMicroseconds(2); }
  }
  
 if (QRE_Value< 150 )  // < 650 means white line
   {
   Stop();
    delay(20);
   BACKWARD();
    delay(10);
   } 
  
 
}


//--------------------------------------------
void FORWARD (){

    //analogWrite(E1, 255); // Run in half speed
    //analogWrite(E2, 255); // Run in full speed
 
    digitalWrite(I1,HIGH );
    digitalWrite(I2, LOW);
    digitalWrite(I3, HIGH);
    digitalWrite(I4, LOW);
    Serial.println(" mprosta");
}


//--------------------------------------------
void BACKWARD (){
  
  
   // analogWrite(E1, 255); // Run in half speed
    //analogWrite(E2, 255); // Run in full speed
 
    digitalWrite(I1, LOW);
    digitalWrite(I2, HIGH);
    digitalWrite(I3, LOW);
    digitalWrite(I4, HIGH);
    Serial.println("piso");
}

//--------------------------------------------
void ROTATE (){//RORATE LEFT
   
   // analogWrite(E1, 200); // Run in half speed
   // analogWrite(E2, 200); // Run in full speed
 
    digitalWrite(I1, LOW);
    digitalWrite(I2, HIGH);
    digitalWrite(I3, HIGH);
    digitalWrite(I4, LOW);
    Serial.println(" stript");
}


//--------------------------------------------
void Stop(){
  
   
 
    digitalWrite(I1, LOW);
    digitalWrite(I2, LOW);
    digitalWrite(I3, LOW);
    digitalWrite(I4, LOW);
  Serial.println(" stamata");
  //delay(2000);
}