Issue getting sensor information through bluetooth connected device

Other Hardware Sensors
1

Hello,
i have an arduino micro connected to bluetooth and to one sensor.
The aim is to get information from sensor through bluetooh console (android mobile)

#include <SoftwareSerial.h>

#define rxPin1 10
#define txPin1 11
#define rxPin2 0
#define txPin2 1


// set up a new serial port
SoftwareSerial mySerial =  SoftwareSerial(rxPin1, txPin1);
SoftwareSerial BTSerial =  SoftwareSerial(rxPin2, txPin2);
int i;

char CaractR; 


void setup()  {
  // define pin modes for tx, rx, led pins:
  pinMode(rxPin1, INPUT);
  pinMode(txPin1, OUTPUT);

  pinMode(rxPin2, INPUT);
  pinMode(txPin2, OUTPUT);
  
  // set the data rate for the SoftwareSerial port
  mySerial.begin(19200);
  BTSerial.begin(9600);
  mySerial.flush();
  BTSerial.flush();
}

void loop() {

  
  if(mySerial.available()>0){
  CaractR = mySerial.read();
   Serial.println(CaractR);//print in windows console
   //BTSerial.print(CaractR);//print in bluetooth device (android mobile console)
   
  }

  }

with that code i am able to get information in windows:
it looks like that in windows console:

1
7
.
5

R

1
7
.
5

R

1
7
.
5

R

this is what is expected! so everything is all right until now

1/
Issue is when i try to get the information throught bluetooth.It does work but only when i manage to get information flow at a lower speed. Issue here is that speed of information from sensor is too fast for bluetooth reception console!
I can make the information slower using delay(200) for example in the loop BUT the information from sensor goes mad after few second (stops or show bad characters).. i guess i cann't use delay to lower the speed because it kind of dezinchronise data from sensor and end in a bug.
How can i proceed to lower coming rate ?

2/ (extra question)
what is the best way to get the 4 character concatenated?
like string data= CaractR (concatenated)= mySerial.readuntil space after two charac +.+ one charact(17.5 for example);...

Cordially

Bastien :wink: