Is it too late to start tumbling ?

I would say it is much to late to start on competitive team and be successful (even getting on a team at your age would be hard). But, you can still get better by doing more of rec, and moving up through the classes. Remember, tumbling is great exercise, so if you want like it, and can afford to keep going at it (I honestly don't know how expensive just tumbling classes are, anywhere). But do not waste your time and money on competitive team, it is just to late for your age and your skill level.