I was diagnosed with Major depression at age 10. I'm now 24 and have survived 3 suicide attempts.
Take it one day at a time. Focus only one what you have to do for that day instead of obsessing over the future and then becoming overwhelmed.
Music is a life saver. There are countless playlists on youtube featuring hour long or more songs for relaxation/meditation. Alternately make a station on Pandora for relaxing music. I have one set up for piano music that I can listen to for hours! It's up to you if you wanna have adblock running if you don't already have a subscription but the commercials certainly don't help. If you'd like, I can email you the station I have set up, just pm your email. :)
You need a support system. Even if it's just one person, find a friend, a family member, a psychiatrist, someone who will listen to you and be there for you. There is no need to feel embarrassed about asking for help. Clinical/major depression is a legitimate illness and having it doesn't make you any "weaker" of a person than someone who doesn't.
Exercise, diet, and sleep. These are some of the most important things to keep up, yet they're also the most frequently ignored. Take a 20 minute walk each day, get a set of weights and do some basic strength exercises for your arms. I have a pair of 5lb dumbbells and spend maybe 10 minutes a day lifting just to keep myself moving. If you have the extra energy, starting a more intensive exercise regimen will help a lot. You'd be amazed how much diet impacts our mood. I'm particularly sensitive to caffeine and sugar and so have to limit how much of that I eat. Pop over to /r/eatcheapandhealthy if you're on a budget but essentially just eat less processed foods. Instead of cheeze-its have an apple. Instead of Mcdonalds throw some chicken in the oven and saute up some veggies. There's no need to completely eliminate junk foods from your diet but they should be lessened of you're eating lots of them. Adjust your schedule to allow for a consistent amount of sleep. Go to bed and wake up at the same time each day. Nothing will ruin your mood faster than sleep deprivation! If you drink anything caffeinated, try not to have any of it after 3pm if you have issues sleeping or consider cutting out caffeine altogether.
Sometimes we just need a day to do nothing, to stop "trying" and give in to the exhaustion. These "mental health days" can help relieve built up stress from the effort of being "normal" everyday. The important thing is to not let it continue. Give yourself a day or two, then get back to your daily routine.
I definitely recommend seeing a psychiatrist. They'll be able to best determine if you need a medication and which one would be best for you. Don't give up if you don't find one that works for you at first. I've tried Amitryptaline, Zoloft, Buspar, Effexor, and Wellbutrin. Amitryptaline did nothing, Zoloft made me suicidal, Buspar gave me horrid panic attacks, and Effexor gave me serotonin syndrome. Wellbutrin though has been a godsend. I have no side effects from it and can more or less function like a normal person. I still have depressive episodes but they're far less severe. What works for you might be different, for example my fiance does wonderfully on Zoloft with no side effects.
I hope some of this helps. Stay strong and keep fighting, you can beat this. :)