I2C device responding, but data is nacked
You want to get the resulting code working, but you should do small minimal tests.  

Start with the i2c scanner.
Connect only one sensor, and if it is detected, add more sensors.

How long are the wires, and what is the value of the pullup resistors ?
Perhaps you have too many modules with sensors, and the total pullup value it too low. The I2C bus is specified for maximum 3mA pull down current.

Do you have a more common 3.3V Arduino board ? For example the Arduino Due or the Arduino Zero ?