Cut part of cartilage in the nose (at the middle of nose) but not putting anything in, can my nose hold its new shape?

What you are describing is called a 'Reduction Rhinoplasty'. This can be accomplished and if done well with a conservative technique the nose will hold its shape very well without the need for adding any cartilage. RegardsDr. J

I need photos to discuss your problem. Otherwise it is just a guess and of no value.                      

Hello unqiueccc, thank you for your interesting question.  In general, to decrease the size of the nasal tip, cartilage trimming +/-  cartilage suturing techniques can be used, and tip grafts with ear cartilage may also be needed to increase tip projection.  To decrease the width of the nasal bridge, osteotomy may be indicated if you have wide nasal bones.  Without seeing your photos, it's really difficult for me to conceptualize your question.  It'd be best for you to consult in-person with a board certified plastic surgeon specialized in Asian rhinoplasty.  Best of luck!