Okay, first things first.
Before you do anything else you MUST remove this from your void loop…
Calling the sendSensorData function from your void loop will immediately flood the Blynk server.
You should read this…
and set-up a BlynkTimer to call the sendSensorData function - probably about once every 1000ms.
YOU NEED TO MAKE THIS CHANGE BEFORE YO7 DO ANYTHING ELSE!!
When you’ve done that, you should read this…
I suspect that your issue falls into scenario 2, an old library version and not having your three lines of configuration data at the very top of the sketch.
Pete.