How to fix wide, upturned nose with prominent nostrils? Surgery vs. fillers?

You have very common characteristics of Asian noses which includes a very flat nasal bridge, bulbous tip, and likely lack of tip projection.  Defining the dorsal aesthetic lines by augmenting your bridge either with filler or surgery will definitely make your nose appear narrower.  However, there are more limitations on what you can achieve with filler on the nasal tip.  The nasal tip will only accommodate so much augmentation with filler and although it can increase your tip projection, it is unlikely to make your tip appear narrower or more refined.  Surgery is the only option to achieve that.

It is also difficult to determine whether your nose is short or rotated given the lack of profile photo.  However, you can derotate or lengthen the nose if needed surgically.

Hello and thank you for your question. I recommend finding a board-certified plastic surgeon here in the U.S. who has experience in ethnic rhinoplasty for your procedure. This way, you can do all your followup with the surgeon after your procedure and you have a local doctor to call if any complications arise. There are many surgeons in the U.S. who have performed numerous ethnic rhinoplasties and can produce the results you want. I also would advise against fillers for your treatment, since this treatment typically adds to the size of the nose. Surgical rhinoplasty can be tailored to your precise needs and facial proportions and the results will be long-lasting. 

Nonsurgical rhinoplasty can be used to reshape the nose by adding volume to the nose.  With regards to the tip of the nose, some degree of refinement is possible to reduce the appearance of bulbosity or width of the tip of the nose, but this is limited by the thickness and extensibility of the tip skin.  Often the tip skin will only allow for a certain amount of projection and refinement with fillers.   Strategic placement will often allow for rotation of the tip of the nose, but counter-rotation, or lengthening the nose, is often not possible to any significant degree with nonsurgical rhinoplasty. 
For reducing the flare or width of the nostrils, alar base reduction/alar base modification is the most effective, permanent option.