What is going to happen to me if I was caught with 1.6 grams of marijuana/paraphernalia but I was not arrested?

A warrant will be put out for your arrest and it will follow you wherever you go. You could get pulled over for speeding 5 years from now and taken into custody in another state until you post bond here in Missouri. This is not going to go away.

You need to hire a criminal defense attorney to handle this for you. Your attorney can probably get the charge amended to "Littering" or dismissed after you complete a drug education class. The outcome depends on your age, your criminal history, the experience of your attorney, and which court this is being prosecuted in.