I think I will post the link to the instruction videos on the Student's Corner as well, because the material is rather unique. My own teacher is very interested in ergonomics, but truth is that it is rather often neglected. You learn the basics in your first lesson and then you play on and on for years, until you start to get hurt. When you start to work with real demanding pieces, maybe for hours every day, you will be in deep trouble if you are doing it wrong. (I'm talking from own sad experience here.)
Of course you can play contemporary music here. But let's look from this perspective: Most modern pieces/arrangements are easier than the classics, on intermediate level and up. Both your featured pieces here are in fact quite easy - technically. BUT - you play them beautifully and, most of all, who said that simple pieces are not good music? Today I played a little walz by Merikanto, and it is very easy and simple, but my husband immediately commented that it was wonderful. So I'm far more delighted by a real good interpretation of "Ballade Pour Adeline" than a limping version of Waldstein Sonata, that's for sure!
I don't think you should think too much about your age and your "chances" to become a professional pianist. Who knows? In order to be a real good musician, you have to have some life experience as well, that's my opinion, and that will compensate for what-you-did-not-do-when-you-were-younger. Just go on playing and be happy, go with the flow just as you already do, and you will see what happens.