It is entirely possible that you may later decide on a career that has nothing at all to do with your college education. My bachelor's, master's, and expected doctorate have absolutely nothing to do with each other. Your college experience does not have to dictate the rest of your life. Life is a journey, and things are going to happen along the way that will inspire you to do other things.
My advice, as I used to give to all my undergrad students, is to focus on the present. Study hard, stay involved in extra-curriculars, and stretch your liver beyond it's preconceived limitations. It is a rough time, but it's also a great time.
Whatever you're doing, just remember to keep doing the best you can at where you are right then. The rest of life will just fall into place. There's no way you can foresee any changes or opportunities that may come your way. In the meantime, there's really nothing wrong or futile about working hard where you are now, because right now, those are your responsibilities.
I personally think the future isn't worth fussing about because we have absolutely no control over it. However, there are things you can do in your present that will help allow for an array of opportunities. You're already doing those things (work experience, good grades, etc.) Just maintain those, and you should be okay.
And when that moment comes where you know exactly where you want to go in the next step, dive for it. Also, remember, that next step doesn't have to be the ultimate step. Like I mentioned, my life has taken me in all sorts of different directions. The following step could be something you never thought you'd do before.
Anyway, that's all I had to say. Just keep doin' yo peef thang.