Also I'm using serial1 because the pro-micro is a leonardo derivative
I'm not looking at the same thing you are, then, because I don't see that. It's time for you to post some links.
I don't understand what you mean, I need to read all bytes to check the serial number from the sensor to make sure it's mine.
In the same way that you can't read my reply until I get done typing it, you can't read serial data before it arrives. You are testing that there is at least one byte of data, and then assuming that it is safe to read 34 bytes. It is quite likely that there is exactly one byte available to read, so you will be stuffing your array with 33 -1s.