What finland needs an army for? (Jk)
If you would only go out to the world you'll find who you are very quickly, don't be afraid, almost everyone question their identity at some point in life. Sometimes you discover your passions at 15 and sometimes at 40 and its OKAY and we can live life without having to fit ourselfs into society's little boxes. The world is a DIY.
Your behavior isn't steady and it annoys you due to what your going through not because you're stupid,weak or any other bad thing we all say to ourselves.
Ive been there too,insecurity made me say so many things i shouldn't have said, share too much with the wrong people and act as if i'm the stupid blonde type people made me feel i was, and believe me i made a fool of myself so too many times.The only reason i found out what kind of music i like and what are my passions is because i started to live and gain confidence and up until that moment i suffered from the symptoms of insecurity (some are as i mentioned above)just like you and couldnt find who i am or what i like.everyone suffer from insecurity symptoms at one point or another in their lives. for one its for a hour when he speaks a foreign language,for another its a full evening when he's suddenly in a room filled with better looking people than him and for some, like you and me, its more than a second of insecurity- but the symptoms of all of the above are the same and we all act and say stupid stuff and cant keep our mouth shut when we are insecure or trying to blend in.
you can not judge who you are and how you behave or be mad if you fail to find yourself, believe me- you only hate your insecurities..
You are young, you are 19 years old and truth is, you are still that little kid you miss so much and if you'll get the chance to live and get confidence he will come back to you in a second and you will be so surprised from how much of a strong steady identity you'll evolve.
I went through the exact problem as you do now, and i can tell you from my experience- these are only symptoms of insecurity which i had (and still have sometimes) too,this is not who you are, your awareness is enough for me to understand that you are not dumb or weird, just suffer from the stupid symptoms of insecurity.it will be very easy for you to find your place in this world if you would only get the chance to experience life.
Btw the reason i want to ctb is because i know but cant be who i really am.
I hate how i act now as well but i know the source for this awful behaviour of mine is bitterness..
dont define whatever problem is yours as who you are, be pissed at other people if they define you at such a low point.
Good luck :)