Just keep on going like you are now. If you see a little problem, just think of something for the time being and look into it afterwards. If you reached a decision regarding the problem then inform the players and all is good.
Regarding the work load, I don't know how often you are playing but since you're at a campus I'd say you have plenty of school work aside from this.
My group and I started a second campaign under my wing so our first DM can keep up. One week he was DM of his campaign and the week after I was DM of my campaign and so forth. That lessened the strain on him. At the moment I'm busy with my graduation so my time is extremely limited. I had to make the call to switch my campaign from once every two weeks to a monthly schedule for now.
Being a DM is tough some times but if your group is a merry and fair one and they allow your space to work then I shouldn't be that worried. If something ever comes up then the forum will always be here for you ;) .
Also, as some already mentioned, whatever you plan will not go exactly as you plan it. So instead of planning things down to the last detail while you expect your party to do A, plan it somewhat detailed but keep a couple of back-up ideas in case your party does B. Mainly, preparation is nice to have and you should have it really but thinking on the fly and improvising situations is a must.
If you don't like being put on the spot like that (and believe me I dislike it) then just start improvising small things like NPC encounters. Eventually you're able to improvise an entire city if need be (bad practice I know but didn't have a choice. Damn party xD)
I wish you good luck and you're always welcome to send me a message if need be :)