I'm Asian and I have a dorsal hump on my nose. Should I choose a doctor that specialises in Asian rhinoplasty?

Although you appear to have a hump, that is only a one part of the problem. Your nose, like most Asians, has a dip in the area between your eyes (radix) that needs to be augmented. In addition, your tip cartilages are soft so that it is slightly dipping downward. I suspect it plunges when you smile widely. The tip cartilages need to be strengthened and also the height needs more projection. This will give you the straighter profile that you are seeking. Augmenting the radix and increasing the tip projection on a nose with soft cartilages are two characteristics of Asian noses that are not commonly encountered in a routine rhinoplasty. 

A common mistake patients, and some surgeons, make while addressing an apparent "hump" in Asian patients is lowering the hump to straighten the nose.  While this may make your nose appear smaller and straighter on profile view, it will appear wider and flatter from frontal view because it is lower.The area of the bridge between the eyes, and above the "hump", needs to be built up slightly while lowering the "hump" slightly to give you a balanced, attractive result.  You will have the best results with a rhinoplasty specialist with expertise in Asian rhinoplasty. 

I think your goal is achievable with basic rhinoplasty techniques.  Some surgeons say they specialize in Asian rhinoplasty.  You should go on a few different consults with surgeons in your area well known for their rhinoplasty work, and not necessarily concentrate on those who promote themselves as Asian rhinoplasty experts. There are plenty of excellent rhinoplasty surgeons in Los Angeles.  Since there are also a large number of Asians, I can assure you that the top rhinoplasty surgeons also have plenty of experience with Asian noses.