I have this big problem with my teeth, or it's my face. Whenever I smile in pictures, my teeth look so ugly! (Photo)

I can clearly see why you are unhappy with your smile but you are certainly not ugly.  You have a very underdeveloped upper jaw (Maxilla) which results in a narrow 6 tooth smile and dark buccal tunnels.  Ideally your would have had expansion before 7 or 8 years of age.   As an adult the best method to correct this is Epigenetic Orthopedics/ orthodontics with the DNA Appliance.  It is also possible to do Rapid Maxillary Expansion with a surgical assist, the SARPE procedure.The DNA Appliance will grow you orthopedically and improve your airway while producing a full wide healthy smile that will support the soft tissues of your face.  It will diminish the nasiolabial lines.  It can also cure and/or prevent snoring and sleep apnea.Ira L Shapira DDS, D,ABDSM, D,AAPM, FICCMOChair, Alliance of TMD OrganizationsDiplomat, American Academy of Pain ManagementDiplomat, American Board of Dental Sleep MedicineRegent & Fellow, International College of CranioMandibular OrthopedicsBoard Eligible, American Academy of CranioFacial PainDental Section Editor, Sleep & Health Journal

Member, American Equilibration SocietyMember, Academy of Applied Myofunctional Sciences

Your front teeth are beautifully aligned--the side teeth drop off so there is no flow of the tooth smile into the lip smile.Your options are to orthodontically widen your back teeth or to look at reshaping them so they are brighter and more prominent. See a good cosmetic dentist and they can even show you what that would look like before you decide--Good luck!

What you're describing entails so much that no one can give you a true assessment of your "problem" without first having a comprehensive conversation with you. There are many reasons and factors associated with your teeth/face that cause you to think you look ugly. ( which, btw, you don't) What I would do is sit down with you with a photo you don't like and hear what it is you think makes you look unfavorable. Until then, any answer would be speculation. If you want further input, please get in touch with me. 

The problem is the narrow upper maxilla, and the only way to correct this is with a combination between surgery and orthodontics, it takes at least 1 year, that way you will expand the posterior area, and your teeth will look more aligned, the size and shape, its ok, but it will certainly will look more nice and even, now, if you would not think about doing braces, or surgery, you need to think about veneers, on anterior teeth, the problem is that you will need to grind your teeth, to make them smaller, but you will have a much better result. and now you will love your smile, and the best is that it can be done within 1 week.