Hi, Krissa. Good for you for tackling the contest environment. Contests are great because they are good motivators…and they force you to decide on a specific set of tunes, notes, and bowings.
But as far as what specific tunes you should pick, I’d say start with what you know and bucket your bag of tunes into the three categories. Keep in mind you will likely need to pull together at least two rounds under the time limit. If you are short a tune or two in a category, I would recommend taking a look the rounds played at a couple of similar contests in years past and then picking a few tunes that are within reach to practice up.
Best of luck, and don’t forget that contests are just a means to an end (like sheet music).
C