Wondering about Anxiety

[Macke]

Hello, I'm an 18 year old guy from Stockholm and I wonder if people could to give their opinion and advice on my situation.

My current bout of anxiety started in November 2013 when I had some kind of anxiety attack when I was studying physics and drinking too much coffee.
Immidiatly afterwards I had so much anxiety that I couldn't eat and barely drink for several days, although I slept well, and had my freind over to watch movies.
The next weeks were filled with almost constant anxiety, and towards the end of the week I had developed issues with sleep.
I got to meet a psychiatrist and a psychologist very quickly (for free, yay Sweden), and I got prescribed 25 mg of zoloft once a day, which removed all my physical symptoms, leaving me with only anxiety.

Now was december, and I was in an alright shape, I could go outside and have guests over and everything, and for the next few months I largely stayed inside as usual, and didin't go to school.
In the summer I would say the constant backround anxiety went away, which left me with only minor OCD, hypochondria and severe existential anxiety(turns out reading philosophy when you're anxious is a very very very bad idea.)
So after a year of doubting my own existance, and weaning of the zoloft, I am where I am today.

My anxiety has gotten worse since I stopped the zoloft, but I'm starting therapy now. Recently I had a bad bout of hypochondria as a result of my physical symptoms making a return due to me quitting zoloft
and I even had to fly back from Turkey this summer in order to get my heart checked out, and I for the first time was too scared to board the plane back, so now I'm at home this summer instead.
I developed a strange condition where I would get dizzy when outside on a large street or shopping mall, which seems to have gone away now, also too scared to drink coffee, even though I did drink alot of it this winter. Also too scared to drink alcohol.
I often become aware of my own breathing and start breathing wierdly until I manage to distract my self.

I've been diagnosed with Anxiety, but not a specific disorder, my therapist calls what I have a "mixed anxiety state" perhaps resulting from being new at school.
When I was 14 I had a similar bout of anxiety, that time lasting maybe 4-5 months until it went away by itself, that time caused by the same reason.

So my question is, what kind of anxiety do you think I have and what severity does it have compared to you and others?
Also, can I expect my anxiety to roughly play out the same way as my first episode, where it went away by itself, as I've only gotten better with the exception of quitting zoloft.
Should I got back on zoloft or not?

Thank you very much for reading, excuse my bad text composition, english is not my first language.