Doubt while Meditating regarding Breath

When i am meditating, my breath which was normal(means three seconds longer both in and out), is becoming one second long or only half second long(extremely short in length). How to manage if breath becomes so short in length, am i going in right manner of meditation ?. **note:** could any body say if i am going or doing meditation in intended manner.. or is there anything i could do to improve my situation or psychological state