@pam I went though an exploratory stage (I'm probably still going through it) as well where I looked into lots of different avenues for my art, so I get where you are coming from- it is bewildering and difficult knowing where to even start and it takes time to explore creatively where you feel happiest. Don't get discouraged. Your illustration- especially the watercolor, looks like it might be good for magazine / editorial work to me, and I heard this is a good place to start with getting into Illustration.
Regarding Concept art- it's an intimidating subject but looks really interesting. I bought a book a while ago when I was looking into concept art: The Big Bad World of Concept Art for Video Games: An Insider's Guide for Beginners. https://www.amazon.co.uk/Big-World-Concept-Video-Games/dp/1624650201/ref=la_B00WFISEBM_1_1?s=books&ie=UTF8&qid=1510679200&sr=1-1. It has some great information. There are also channels on youtube which might be useful to give you an insight into concept art like FZD School. https://www.youtube.com/channel/UCbdyjrrJAjDIACjCsjAGFAA.