It sounds like you're so used to working hard on that thesis, that you don't know what to do with your time now that's it's about finished. I remember when I handed in my undergrad thesis - I just tried to enjoy some time off and did things that relieved some of the stress and worry about the upcoming defense. Maybe get into some healthy habits such as exercising or taking walks, reading a good (non-academic) book, go out with friends - or if you really want to work on something, see if there is a lab that you could help out in to strengthen some relationships with profs and peers before graduation. Building a strong network will help during the job hunting process, as well as after you find a job and consider advancement.
Keeping yourself busy sounds like it's an important way to keep your mind off of your depression, since you say it relates to the slow process with your thesis. But that doesn't mean the busy stuff has to be academic or stressful, unless that's really how you want to spend your time. Maybe even take a walk down to the college counseling services office and make an appointment to chat about some of your feelings with a counselor.
I'm sure you'll do fine with the finalization of your thesis and defense, and I wish you luck with finding a satisfying job. It must be exciting to be so close to the end!
"Life's journey is like driving at night in the fog.
You can only see as far as your headlights,
but you can make the whole trip that way."
Chronic Lyme, Depression, Anxiety, 12+ Years