You're incorrect in the feeling that everyone is depressed every so often. Sadness is a normal feeling - everyone gets it, and to an extent I might even say it's healthy. Depression is not sadness; it's not just feeling blue. At its worst you feel absolutely nothing. In my case I have been dealing with that feeling to varying extents every day for years. It nearly drove me to suicide last year, at which point a friend made me see a doctor. It is a legitimate medical condition, not just a feeling.
I am doing things with myself: I'm a third year at university studying engineering, previously I have been a volunteer student leader helping first years as well as organising groups of international students on a weekly basis to exchange culture and speak English. I have a mentor with over 40 years of industry experience, as well as 3 degrees (Engineering, Science and Economics) who is very charismatic and who is at this point probably more important for my career than my actual degree. He also lets me drive his Tesla Model S, which might I say is an amazing drive (there's only like 20 of them around the place here atm, so it's pretty exclusive too).
I do plan to take next semester off or maybe part time at university so I can focus on getting some work and sorting myself out. As far as girlfriends are concerned, I've got a sort of FWB thing going on with a polyamorous friend of mine, and I'm on the lookout for potential partners, the main barrier is my aforementioned anxiety (something which smoking weed has helped me a lot with. I feel a lot more comfortable in my own skin since I started smoking it). Things are looking up, certainly, but I'm not out of the woods and I'm one breakdown away from seeking more specialised psychiatric help.