Keep in mind I don't have any actual IM experience, but are you saying you have 1 gram per 10 ml (= 0,1 g / ml )? Because then 200 μl (not ml) would indeed translate to 20 mg which should be a light experience.
Are you familiar with taking stuff IM wise?
If you are I'd certainly wait another 10 minutes to be sure and then try another 20 or 30 mg.
Also, if you want to know if you dosed right you need to give some information about what you did: what does the vial say and what was your technique?
I mean if you injected it, it hasn't disappeared so you're missing something regarding the dosage or you're not sensitive.