It sounds like you're right on track. The best way to see if you are fast enough is to try and go race, but it sounds like you should be. Riding 3 to 5 times a week is plenty training at your age and experience level. Remember, it's not neccesarily the quantity of training time that counts, but the quality. Work on some long rides for endurance (30 miles sounds perfect) and some shorter, high intensity intervals and sprints for speed. Over time, you can begin to extend the duration of your rides, assuming your schedule allows. Also, Don't forget to allow yourself recovery days after your hard days. It also sounds like you have some riding experience with groups, and that's important for racing.One thing that helps a lot is getting on a local team. A lot of teams have junior development programs where they can help you train, give you some knowledgable guys to ride with, and even get you some clothes and stuff to race in. Got to your Local bike shops and ask about local teams and see if any have room for a new junior. Most importantly, don't get too caught up in training, make sure you're riding to have fun and be healthy. I am also a junior racer, so if you have any more questions, let me know.