First please learn to format your posts in stead of just dumping a lot of text in a message.
Regarding your MQ2, I would look into writing code that works alright to get the sensor value and write it to the serial port and next incorporate it into LoRaWAN code. That way you only have to debug one issue at a time.
BTW, showing a screen that shows a value 21 is not useful without telling us what you expect and why that value is wrong.