Is it possible that at 15 months post-op my nose will refine much more & the tip become less bulbous & the hump go down?(photo)

Therefore your nose will change little in the with further time. You appear to have a poly beak with a droopy tip and the excess cartilage above the tip is too high. You need to see an experienced revision rhinoplasty specialist for this. This will not change with more time. Look at good before and after photographs of revision patients. 

I doubt you will see any more changes to the appearance of your nose at this point.  I would begin researching board certified facial plastic surgeons that has experience with revision rhinoplasty.  Ask to see before and after photos and don't hesitate to ask to speak with references.  Good luck with your search!Mark Petroff, MD  

At 15 months, it is unlikely that you are going to see any major changes occurring to your nose.  Much of the swelling and healing happens within the first year. That being said, small changes that you and your surgeon may notice will continue to happen years after the rhinoplasty. It does appear from your photos that you do have some fullness in the supratip region which may be due to scarring or excess cartilage. As for your breathing, this requires a detailed examination to identify the exact problem that is causing this. I would recommend seeing a revision rhinoplasty specialist as they will be able to treat your breathing and cosmetic concerns with your nose.

I would say that 15 months after surgery, no significant changes will take place. It is true that if you did nothing and took photos in 5 years, there would be some differences. That being said, I do not think the issues you are referring to will necessarily improve with time. An in person examination is necessary to go over in more detail, but from your description and the photos, you would need a revision surgery to correct these issues. I would recommend finding an experienced revision rhinoplasty surgeon to sit down with and go over your options. Best of luck