your 6 second delay did nothing to help you .
what you did was to get sensorLreading.
wait 6 seconds
show what the sensorLreading was
void loop() {
int sensLreading = analogRead(sensL);
sensLreading = analoRead(sendL); // second time
int sensRreading = analogRead(sensR);
sensRreading = analogRead(sensR); // second time
delay(500)
Serial.print ( "left reading is = ");
Serial.print (sensLreading);
Serial.Print(" right reading is = "); // extra spaces in front to separate from the sensLreading
Serial.println(senRreading);
then move your LED , put a tube, a straw or some cardboard around the LED and the LDR to block any extra light.
get the highest reading you can, and the lowest you can.
that would be a way to calibrate your LED to LDR values.
also, if you read the same value twice, the first time may show some effect from what was read before.
the ADC needs some time to settle. between readings.