Am I depressed?

[Jeremy1012]

I'm an 18 year old student who is currently finishing his final exams.

I am a very pessimistic person who believes that I can achieve nothing. I'm not sure what started my "depression" but I've been very unhappy with myself for the past 3 years. I am extremely sensitive, over-caring and I get attached very easily. I have "fallen" in-love with a few of my female best friends over the past few years, I am currently "in-love" with my best friend now but I'm positive she doesn't look at me the same way. It's always been like this. I have been in a few relationships that barely lasted mostly because they used me to get with friends and so on so forth. I am not confident what so ever.  I over-think constantly and I tend to believe the fictional thoughts that I brew up myself more than the actual factual thoughts. I also am not able to show any physical comfort to anyone as I truly feel it's unwanted or inappropriate.

School is also a major problem for me, I am "brilliant" student my teachers tell me even though I don't see it, my exams have lead me to set dates to end my life If I didn't succeed into getting promoted and what not. I get very stressed but I don't really show it except when I'm alone. I have many caring friends and I have a great family with 2 loving cats but I feel empty and have been feeling empty for the past few years. I truly believe that I'm worthless. I have had people comment on how I always appeared to be happy at school and what not but in reality I just suppress my true feelings. I used to cut but I haven't in a year, I do not have the urge to go back but I've started drinking and smoking more which doesn't really help at all.

I have a great sense of humor and I normally laugh at myself with regards to the situation I'm in and the previous ones I've been in. I enjoy making my friends laugh and smile but I truly feel like it drains me on most occasions.

I'd appreciate any helpful comments or pieces of advice from the community.