Congrats on having the balls to get out there and test yourself.
There are few of us who train, even fewer who compete in front of people.
Prior to my twelve fights in MMA, i competed in countless BJJ tournaments. Honestly, experience cured the adrenaline dump for me. You learn the prep, learn the flow of things, know what to expect, etc.
For instance, I could always tell the new guy from the seasoned fighter backstage. The new guy would be pacing around and shadow boxing hours before they went out to fight. After a fight or two I had my sneakers off and a hoodie up with my iPod in relaxing on the floor.
We've had plenty of guys over the years that were studs in the gym but froze in competition and never went after it again.
My advice would be to compete as much as possible and don't put so much pressure on yourself to win. It will happen naturally, just embrace the grind.