DC motor with L289N driver cannot set RPM lower than 130
Looks like you are controlling two motor outputs via the H-bridge, where the logic inputs are in1,in2 and in3,in4.  First of all, you need

pinMode(in1,OUTPUT);
pinmode(in2,OUTPUT);


One reason why the motors may not spin for analogWrite value less than 130 is that, coincidentally, the voltage output is too low and motor stalls.  Test this two ways: does (1) changing the motor supply voltage or (2) changing the argument of analogWrite actually change the speed?  

If no, it may be that pinMode(enA,OUTPUT); sets the output as digital and should be removed.  In that case a number less than 128 gets interpreted as a logic 0 and the motor will not spin.

P.S. your code can be neatened up using port syntax and bitwise operators.

digitalWrite(in1,HIGH);
digitalWrite(in2,LOW);


can be written on a single line with

PORTD |= _BV(in1);


Also

digitalWrite(in1,LOW);
digitalWrite(in2,LOW);


becomes

PORTD &amp;= ~(_BV(in1) | _BV(in2));