You should ask your coach about this. You don't want to work really hard and have your sights set on level 5 and then find out that your gym requires that everyone do a year at each level, or something like that. I know at my gym they would probably have you in Xcel (prep-op) due to your age unless you specifically requested to be on the JO team and they thought you had enough talent/drive. Most older gymnasts are looking for a more casual experience.
Of course there are super-quick success stories. One of my friends is a level 7 who has only been doing gymnastics for 2.5 years. Another friend did level 5 her first year on team, and then did both level 6 and 7 the next year. BUT most level 6 gymnasts have been doing gymnastics for at least 3 or 4 years, and the jump between level 5 and 6 is bigger than you think. Progressing through the lower levels really fast typically happens to people who are "born to be gymnasts" and obviously I don't know if you are or not. Don't worry about it, though. I started gym seriously at 13, like you, and I wanted to get to level 7 as quick as possible...it still took me 3 years, but I learned so much in the process. I wouldn't want to go back to practicing with 7 year olds now, but it's just something you have to work through if you want to stay in gymnastics.