What do think?

Here is a good one for you all. I have a great job which I love going to most of the time. There are days where I think am I supposed to be doing this? Am I wasting my time here? Is this what I’m suppose to do? Is this it?
I have found out of the years of working different jobs that I love to a lot of stuff and not just one thing. Some have called me “Jack of All Trades but Mater of None.” Somone told me I should find something to master and I was thinking what would I master? At this point I mess with a little of everything that I like. From taking photos, to drawing, CAD, designing, learning new stuff, changing photos or pictures, manual labor every once in a while, and driving around in a company vehicle I get to enjoy what I do. There is more but that is some of the ones I think of now.
Is it time for me to find something and maybe go back to school to master something or keep on the road I am seeing where it goes? Most of the time I feel I right where I suppose to be cooling my jets after going to school hard core for 4 yrs but sometime I feel that I am wasting my time here and that if I don’t watch it I could get stuck here in this for life. Where I am right now I feel I should be getting paid more, and can’t do some of things I want to do in the future on the pay I’m getting now.
I’m getting the urge to go back to school to learn more stuff but not for work but for fun. Am I just thinking to much sometimes or is this something I should be thinking about more about?