I am sure that if it goes to the college stage you will definitely get an offer because it's the department that accepts you, not the college. The department knows how many offers it can afford to make and thus if it decides to make you an offer then you will definitely get a place in a college. Even if it is not the college you've chosen that will give you the offer, another college will.
Your application gets passed from college to college after being accepted by the department until one of them has room for you. Colleges don't fill up on first-come-first-served basis but in such a way that there is a mix of people doing different courses.
I hope this helps. Just stay patient and don't worry about it too much- I know that's easy for me to say because I was constantly checking the tracker last year. I'd also like to point out that I got my offer letter direct from Durham on December 11th last year, before it reached the college stage on the Durham tracker and a month before it appeared on UCAS, so it doesn't necessarily mean anything if your tracker hasn't moved from the department yet SiAnY.
Good luck everyone!