Which nose shape would suit my face best?

Great question!  Looking at your wish photos, the model does have a slight slope, its not straight.  Having a slight slope is also a more feminine appearance so I would recommend that for you.  Narrowing the bridge width can be performed with osteotomies (narrowing the nasal bones) and the tip can be refined by removed excess cartilage strategically.  This can all be done in a closed or "scarless" fashion so you will not have any external scars.  You are correct in that a well done rhinoplasty only improves and defines the nose for a nicer appearance and should not give you a completely different nose or appearance.  You seem to be a great candidate for this and your issues are all reasonable.  Seek a few consultations with board certified plastic surgeons, look at their photos, and go with the one you feel most comfortable with.Best of luck and hope this information helps!
- Dr. Roger Tsai  @DrRogerTsai
Board Certified Plastic Surgeon 

You can get a nose much closer to the example noses that you posted. But you have several issues with your nose, and your surgeon must be able to identify and correct all of the issues, or there can be problems -- the nose might overall look worse if only one or two of the several areas are corrected.Your nose is strong in its forward projection from your face. We call that a "projecting" nose. The tip can be brought back closer to your face. We call that "de-projecting" the tip. 
The tip of your nose also sits low, a somewhat "droopy" tip. And you have that bump on the bridge. If the bump is removed, the nose will look even longer, as if the tip had drooped more. So it's very important to elevate the tip of your nose at the time of surgery.The tip also looks as though it is wider than it needs to be, and it can be narrowed during surgery as well.When the bump is taken off of the bridge, that's when the decision is made whether to leave the nose fairly straight or to give it a slope. Personally, I usually like a little bit of a natural-appearing slope.How *much* to lower the bridge, or elevate the tip, or deproject the nose? We figure that out with morphs before surgery. I'd love for you to see some excellent professionally-designed morphs of what could possibly be done with your nose. Morphs could also help you identify what's bothering you, and help you set a goal for the rhinoplasty that's accurate for your tastes. Profile and three-quarter views would be particularly important in morphing your nose. (Side note: in my opinion, morphs should always be done by the surgeon, or he should direct an assistant as she makes the morphs. Morphs should be made with a constant eye to what actually *can* be done in surgery, for that particular nose, and only the surgeon has that information and judgment. Another aside: I also recommend that you not show morphs made by one surgeon to a different surgeon. If a surgeon makes his *own* morphs, you get to see whether he understands the important issues of your nose, and how your nose should be changed. But if you show the surgeon someone else's morphs, and he says "Of course I can make your nose look like that," then you don't really know if he fully understands, or even recognizes, the important changes shown in those morphs. And you don't know if he can make those changes during surgery.)
Finally, remember that rhinoplasty is an exquisitely difficult operation to get right, and you should only have surgery if you are able to make yourself very confident in your surgeon's skills. The changes that your nose needs require advanced techniques, and skill that most plastic surgeons don't possess with expertise. For most noses, it's much better to not have surgery than to have inexpertly-performed surgery. Read my essay on how to stay out of trouble while selecting a rhinoplasty surgeon.  And it also discusses how to take photos that are best for online evaluations.
Your nose is also a perfect 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. I always email morphs to my online rhinoplasty consultations. When you see the surgeon's goals in the morphs, you'll know whether he has an eye for an attractive nose, and whether he shares your opinion of what constitutes an attractive nose. You'll also know whether the changes he proposes are large enough to be meaningful to you, and whether he understands your wishes enough to address all of your priorities. How would you ever get that figured out without the morphs?

Thank you for your question. Your definitely an excellent candidate for a rhinoplasty procedure. The most important thing for you to do is to review potential plastic surgeon's galleries to make sure that you are confident that the results are ones you would be happy with.  Also, make sure that your plastic surgeon is very experienced at rhinoplasty and does several per month.  Best wishes to you.