This will matter further on up the road. Pronunciation, correct pronunciation, is the hallmark of an educated person. In all of your future endeavours you will be judged firstly and most harshly on your ability to communicate the ideas in your head. No matter how brilliant you are and become, if you can't communicate your ideas then you are mute: you will contribute little to society. One of the easiest ways to communicate is through the spoken word, and it is of supreme importance that you be able to say exactly what you mean when you mean it to whom you mean it.
There is an "r" in both "shirt" and "fork". Make a note.