Is it possible to go from a big, bulbous nose to one that's small, even at the tip, like Megan Fox's? (photos)

Jaqueline, Reducing the size of the nose is something that takes a lot of experience.  I lecture regularly on ways to greatly reduce the size of the nose.  Take a look at the video below.  We have many ways to reduce the nose and make it smaller, less bulbous, and less projected.

Click on the "Web reference" link, just below my response, or go here:
FacialSurgery.com/RealSelf/RealSelf_jacquelineledoux.html
I made a computer morph of your nose, and an animation of the morph, to show the changes that are possible for your nose in truly expert hands.
I narrowed the tip of your nose. Your two tip cartilages are strong, and modifying the cartilages can make a big difference in your nose, like in the lady in the short video just above.Megan Fox has thinner skin than you do, and your thicker skin would put a limit on the *amount* of narrowing that you can achieve: your tip can't get as narrow as hers, but what you need is an operation that can get you as much improvement as your personal anatomy will allow.
You should understand that the changes I demonstrated in the morph require advanced techniques, techniques that most plastic surgeons cannot handle.  Be sure to read the section in the "Web reference" link on how to stay out of trouble while searching for a rhinoplasty surgeon. You should only have surgery if you are able to make yourself very confident in your surgeon's skills. Read that page very carefully. Most plastic surgeons are quite poor at this operation, and I believe my advice will go a long way toward keeping you safe.
I'd love to hear what you think of the morph. Did it seem to address your main concerns?
Your nose is also a good example of why computer imaging is mandatory in rhinoplasty. You need to know exactly what the surgeon is planning to accomplish -- what features he thinks he can change, and by how much he thinks he can change them. When you see his goals, you'll know whether he has an eye for a beautiful nose, and whether he shares your opinion of what constitutes a beautiful nose. You'll also know whether the changes he proposes are enough to be meaningful to you, and whether he understands your wishes enough to address all of your priorities. But remember, you're not hiring him for his skills with the computer. The doctor must then show you his before and after photos to prove that he can actually accomplish what he draws on the computer.
In your case in particular, you need to find a surgeon who understands all of the issues I mentioned, and how they fit together, and who can actually accomplish them in surgery. 

Scarless Rhinoplasty is absolutely the answer.   This is the approach all celebrities, models and actresses take because there is no external cuts or scarring.  The goal is to refine the nose, not drastically change the nose.  By doing subtle refinements we are able to finesse the sculpt the nose to match your face perfectly.  By doing this via a scarless (closed) approach, there are no external cuts ever on your nose.  This prevents the dreaded complication of external scarring at the base of the nose, which even if rare, if it occurs, is devastating.  Through a scarless approach you can accomplish almost everything needed to be done to the nose with no scarring, less healing time, less bruising, and less swelling.
However, with this method we would make sure that Megan Fox's nose fits your face well before we forced it to look like this. Every face is different and beautiful, and we want to sculpt your nose so it fits the natural shape of your face. 
All the best!
Deepak Dugar, MDScarless Rhinoplasty ExpertBeverly Hills, CA 9021