I want to start by saything this really is just my opinion / perspective on whats going on. Im no doctor and I could very easily be 'wide of the mark'
It does sound like depression but instead of the "feelings towards him be caused by anxiety/depression" how about reversing it. The depression/anxiety causing the feelings towards your bf. You mentioned that he has been really good to you. He has been supportive and caring but you have "hardly anything to return". Maybe you see the relationship as one-sided and because you feel you have nothing to return, you feel guilty and see this as a reason for the relationship to end. (Hence why you as "Is my relationship doomed?") I think a good long HONEST chat with your bf could clear up these feelings between you. If you had nothing to return then I think he would have gone before now, so you must have something. You are obviously a great person and I certainly don't think your relationship is doomed.
Having a student in the consulting room is enough to make anyone feel uneasy. I certainly wouldnt want it. Im glad that your mum has asked for the student not to be there. This may help you get the most our of your sessions.
Chin up, Stay strong and place one foot in front of the other. You will get to where you are going. Its only a matter of time.