Purpose of life

I wonder,  if everybody has thought what to do in life, or it's only me who's stuck in this questions? . Would people think to be really happy, or they never think about it? whenever i ask my friends this kind of stuff the only answer i get is "why do you make this awkward things?" or "What?, you're really weird person, go away". But it just makes me feel so curios about how people deal with every problem, do they think  a lot ? i see the, passing by everyday, unkowing if they're aware that their life is going in front of them right now.
I don't really know what is my trouble. I'm happy today, sad tomorrow, and the day after tomorrow probably i'll be angry, things happens too fast in life, If i only had the power to stop time and take a breath to calmo down and make better decisions, everything would be perfect. 
I don't get why i change my mind so many times, in only one day. a lot of things are in my head. i get annoyed and stop thinking about problems, go to sleep, but the next day they still there. nothing changes. 
Happiness, what is it? once, i read something where a definition was stated, "Happiness is reflected in short moments, gone really fast, but enjoyable times" 
Advices are never enough. i really need to understand life.
but right now it's impossible, family problems are not big deal, missing someone who will never comeback eigther. 
Be depressed is the worst, call me crazy but somehow i kinda like to be sad, it's the weirdest pleasure, but i can see a beautidul side  of situations from that perspective. Sorry God, i hurt so much my grandmother and i comepletel regret about it, i think i'm anxious to die because i want to apolize her, as i say ot before, call me crazy it doesnt really matter, i wouldn't feel bad by someone telling me the truth, i accept it.