Umit ,
just i read your story .
Abiciğim , don't give up . You are studying at one of the well known University . They are standard is very high . Try it again . İt will not the end of the world . my son did same mistake .he changed his branch because of Differential Equations too . he was studying Electrical and electronic engineering . he changed it for computing teacher .he will be teacher but it will be very difficult for him to find job . may be it will help him for our production company which we are planing to open in few years time .
i can understand your feelings about military service if you give up you will do it as a ordinary soldier but if you finished you will be officer .you don't like taking orders than .