Accelerometer and Bluetooth

Hello everyone, I'm just another newbie struggling with interface problems with bluetooth.
I connected the 9axis-motion module with Arduino Uno and later I interfaced it with the BLE HM-10. The good news is that I can read incoming data with standard applications for both Android and IOS, the bad news is that I was convinced that they should come with a fixed length (20 characters) and if I try to make a single string by combining the single values, i can not separate them in the process of arriving.
Where is the error please? Someone can help me?