You're capable of more, but, I get it. So am I. I used to be so smart and was on track to do #bigthings. Then I got off track, made one really dumb decision and have been riding it the consequences of that ever since. (Joining the army was the worst thing I ever did to myself.) I can't really give you good advice. I can say that sometimes not knowing is a good thing.
Discussion
I've been telling myself, "it's okay to not know" and telling well-meaning, curious people who ask what I can do at the end of my degree, "I'm not sure yet." But, provided I don't fail this semester, this time next year I'll be graduated, then what am I supposed to do?
Hmmm, somehow, I can't imagine joining the army would do good things for you. But I have no doubt recruiting campaigns make it sound amazing.