Think of anything you might have had enjoyed in the past - maybe in school, probably math, or even outside school, like music. See if you can try and work on those and if you still find them interesting, maybe you can enroll in classes or something. Hopefully, it might show you a way. But don't quit whatever you're doing right now. <br />
I had the same question even when I was majoring in a subject related to healthcare- if it really is my calling or if i should be doing it and had sleepless nights over it. I had some pretty bad days where I just wanted to quit and start from scratch but didn't knew what to do when I quit. So i held on to it and graduated anyway. And when my life became too boring, I started trying out new things and in that process I realized that i like music a lot and even considered making it my full time profession sometimes, in the early stages of hyper-enthusiasm. When things stablized and after I got a well deserved break for a while I realized that I like both music and my major - except that I'm not too excited about either. Maybe some people have different levels of enthusiasm, just like my teacher said. I like both, not to the extent that I'll go gaga over them but yes, I enjoy working in both. Now that "my-calling" thing won't bother me anymore. <br />
And one more thing, don't let peer pressure influence you into not exploring new things. I moved across countries when my friends were getting hitched and discovered whole new angle of myself and world while they were having babies. They were earning well then, but I have experienced far more things in my life than they did and have made that experience as my greatest asset. You have more stories only if you try.
Maybe it is best to keep doing what you are doing. It feeds you and gives fantastic benefits and retirement. Things will get better as time goes on. Military life is not so bad once you start having a family. You are in the position of a good standing being that you started so young. You can retire at a nice age. You can get good college benefits.<br />
I hope you have a very good life whatever you do choose!