You also are a Catholic. Your school is not allowed by law to prevent you from attending services sometime in the Saturday/Sunday time frame. It’s the same for a job. There are laws that prevent that sort of thing.
I used to work weird hours at a fairly rigorous job, and managed to work my religious requirements around the schedule just fine and didn’t ever need to use the law, but that’s how I know it’s on the books. Between the Saturday night masses, the early Sunday masses and the late Sunday masses, I was able to catch one okay every time.
But the good thing is, in a city the size of Washington DC, with all the high profile churches there, you can catch masses at a lot of different times of the day. It makes it very easy to get to mass on a tight schedule. You just might have to do some planning.
I remember a trip I had to take for business halfway around the world a few years ago. I used the internet to plan my Sunday mass. I walked right off the plane, into a taxicab, dropped my stuff at the hotel, and continued on to church in a city where I’d never been before–just like that. I love the internet.