I have a small mouth and thin lips. What are my options to make my mouth bigger and fuller lips?

Dermal fillers, such as Juvederm and Restylane, work very well in the lips and can be used to provide both volume and definition.  Both of these products are made from hyaluronic acid, a gel-like material that naturally occurs in the human body.  I would recommend that you seek out a consultation with a cosmetic practice with extensive experience in the use of dermal fillers.  

Thank you for your question. In my office I like to use dermal fillers
such as Juvederm and Restylane Silk for lip augmentation. These are hyaluronic
acid fillers that can easily be dissolved with an enzyme known as hyaluronidase
if you are unhappy with the results. I recommend having a consultation with an
experienced and talented injector to determine the best treatment plan for you.
Best of Luck! 

You can increase the size of your lips with dermal fillers like Restylane, JuveDerm and Belotero. They all will increase the appearance of your lips. Only use skilled injectors who know what they are doing. You cannot make your mouth bigger in a non-invasive manner.