Is it possible my underbite won't get worse?

I'm 19 and have a very mild underbite. The reason I'm categorising it as very mild is that my lower teeth only jut out past the upper if I clench my teeth together. If I smile with my mouth closed you wouldn't know I had an underbite because the top teeth and the bottom teeth touch but nothing sticks out. I guess I'm okay with looking like this, but if it gets worse I know it's going to cause a LOT of problems down the line in terms of my appearance. So what I'm asking is, if my underbite is this way at 19 years of age is there a chance it will stay like this for the rest of my life or will it definitely get worse as I get older? Please don't tell me to see an (forgot the word, he deals with jaws and braces), I already did and I've forgotten the answers he gave to the questions I asked and I don't want to bother him again.