I always find it useful to separate the collection of data from its display. Until you get the data collection, interpretation and control part working don't bother with the LCD stuff as it just confuses the code. Just use Serial.println() to display values in the early stages of developing a project.
I am also a great believer in putting each different activity in its own function rather than in loop(). That way each function is short and clear and easy to understand and debug separately from other problems. As fas as possible I like just to have a series of calls to functions in loop() but no other code.
...R