Don't like small mouth but not sure what I can do about that and don't like my cheeks. What can I do to improve my face? (photo)

Dermal fillers can change the shape of the face in a natural looking way. You have naturally thin lips so adding a bit of volume here would be a great place to start. There are any number of fillers that work nicely (Volbella, Vollure, Juvéderm). Schedule a consultation with a board certified plastic surgeon or cosmetic dermatologist to be examined in person and discuss your best options. 

 Hi, I have performed many facial shaping procedures using dermal fillers, silastic facial implants (cheek, chin), liposuction and/or facelifts for over 30 years.  From the photos, your cheeks are very flat in the front, there is excess fat in the mid and lower face and the lips are thin. These combine to create an elongated, oval shaped face.  
 Following my beauty principles, women look the most feminine, youthful and attractive with heart shaped faces.  Heart shaped faces have cheeks that are full and round in the front.  Cheek augmentation using cheek implants for a permanent enhancement will create full, round cheeks that will feminize the entire face.  Liposuction would be used to decrease the excess fat to further shape the cheeks and face.  The excess facial fat (baby fat) is typically gone by the mid to late twenties.  If you are a teenager, I would wait until you're in your twenties to do either of these procedures.  I have performed many lip augmentation procedures using dermal fillers or lip implants for over 30 years. From the photos, your upper lip is small compared to your lower. Following my beauty principles, the upper lip should be approximately 75 % the size of the lower lip for the lips to appear balanced. The lips can be augmented using a dermal filler or a Permalip implant.
Dermal filers and lip implants offer a much more reliable volume for augmentation of the lips than permanent fillers or fat injections which are associated with increased, unwanted, side effects.
Hope this helps.