I had exactly the same problem as you when I started college.
I managed to find a disabled toilet that was hidden away and on its own (I hate restrooms with gaps uder the doors and loads of toilets)
This helped the problem a bit.
I spoke to the accomodation office about a room with its own toilet and they said they could only guarantee this if I had a specific health issue. I was too scared to say whatmy issue was. But if you are ok telling them with the support of your doctor this may help?
Hope this helps :o)