Hi Sunshine, You have brought up some pretty good points in your post. Your getting ready to graduate college and feeling the stressors from that, it is a huge moment. I dont believe that society puts expectations on anyone to be "perfect", perhaps your family, friends, and chosen carrer path has but not society as a whole.
Now, your asking about "antagonizing factors" and my response would be to eliminate as many of those from your life that you can. Those friends that are not supportive of you and put more stress and pressure on you are not real friends in my opinion. The same goes goes with family members however, it is more difficult to dump family but you have limit the amount of contact you have with them and be aware that they are a stressor for you.
Depression is difficult to maintain on your own without medication and thearpy. Most of it does come down to dysfunctional home lives, parents, trauma of some sort or just plain chemical inbalance. Whatever the cause for it we do have to be aware of what triggers our symptoms and try to avoid them the best we can.