First I'd like to say well done to you! Quite ambitious for being 18. I applaud you.
With an AA degree and a TEFL certificate, you will be able to get work. The concern might be however (get used to this for the next three to four years) that because 18 is considered young, the question might be your level of commitment as far as staying in one place for a one-year or two-year contract.
(I was 18 and ambitious like you and I got that crap all the time
- it won't really ever abate completely - and I'm now in my 30's!)
Good Luck! I hope that helps...