A post like this surfaces pretty frequently. Search the archives and you will find you're hardly alone. My advice is typically, if you dislike it this much at the beginning of schooling why put yourself through a lifetime of misery? School should be a more enjoyable period as you have the most freedom you'll ever have with architecture (e.g. No budget, no boss, no client).

For the record most white collar/service jobs involve sitting staring clicking at a computer - it sucks.

Architecture is really not a "helping" profession.  Your clients are the rich because they are the only ones who commission buildings to be built.  And they really don't need much help.  They are pretty good at helping themselves.  And as for creativity, most buildings are just drab enclosures of space that will serve a purpose for a time and then be replaced due to obsolescence or a better use for the land.

Do a gut check to see if the reasons you wanted to be an architect are valid for you.  If they are, then be assured most architects don't live in the kind of mental misery that you describe.  It's just a job, not a religion.  The profession is poorly paid, unstable, and has a somewhat cloudy future.  It's not the best thing you can do with your life, but it's not the worst either.  Repeat:  It's just a job.

Spend some time in the office of a practicing architect and see if architecture is something you really want to do.

I'm in the USA, so I can't speak specifically about Brazil, but school and the profession are very different.  

Set aside time for yourself doing things you enjoy.  It's something I learned in my third year.  Even though it sounds counter-intuitive, by blowing off studio and going out with friends / girlfriends, I found my grades shot up, my designs got better, critiques were more palatable. etc.  And from that I learned not to stress as much about the program and start enjoying college/life. By my 5th year, I was working weekends at the bar, taking weekend trips with friends, etc. without that sense of dread of a approaching deadline.

1. Spending more time on a project doesn't always make it better. Manage your time to include things not related to architecture and go exercise and sleep properly.

There's also no shame in failing a class or repeating it(20 20 hindsight)

Be more efficient, don't do CAD but BIM, so you're not redrawing all the time and have time for other things like sleep, make models, exercise or eating proper meals.

2. And do what? If you know of an alternative already, why are you still torturing yourself? "Run, Fat Boy, Run!"

3. I took my time, repeated some classes I failed or skipped to work on my design projects, I worked abroad and traveled.