Am i still a consider to be a felon even if my case were dismissed?

I got arrested on a class 4 felony charge 2 years ago on id theft, made first appearance didn't even saw a judge just saw assistant i was told come back next month, called back next month they told me over the phone pay 220$ and my case be dismissed did that case were closed and dismissed. Now i am trying to do National Guard they won't let me in they said that i am a convicted felon even i didn't do no time in prison or saw a real judge in court they said in national guard paying 220$ made me plea guilty which makes me a felon. Ok i am considered to be a felon how come i still can vote and purchase and obtain firearm? it makes no sense to me and get this i was in active duty army when the case were dismissed i served 3 years honorably. I don't get it why it makes still a felon?