I'm a 19 year old guy and I'm pretty sure I have ptosis. Where should I get it treated? (Photo)

Look for an oculoplastic surgeon. You should be candidate for scarless internal ptosis surgery with quicker recovery.

Thank you for your question and photo.  Based on the photo you submitted, it appears that the right upper eyelid is ptotic.  An in-person consultation with a board-certified oculoplastic surgeon can help determine if there is any underlying medical cause of the ptosis, and then determine the best treatment options.

Thank you for posting your question to RealSelf and for providing a clear picture of your eyes!
It is difficult to say for certain what may be going on with your eyelid. Ptosis may be the issue at hand, but an in person exam is usually needed to come to any diagnosis. Ptosis is commonly caused when the muscle that picks up your eyelid is unable to do so. The muscle can detach, which might be the case after hearing your cat story, or it may have become stretched out over time, which is less likely in the case of a young man like yourself.  In either instance, it is important to go see an oculo-plastic surgeon who can perform a comprehensive eyelid examination. After doing so, the surgeon will be able to provide you with clear-cut options and will be able to discuss, at length, your goals for your eyes. Hope this is helpful.
All the Best,
Dr. Dan Landmann, MD, MSEE