The numbness is traveling up my cheeks and feels very uncomfortable. Is it possible that the injection damaged my nerves?

This is difficult to answer without pictures. If you're unhappy with your results, you can have the filler dissolved or a touch-up may give improvement. I recommend following up with your injector. Hope this helps.

Thank you for your question. I'm not sure how much time has transpired since your injections. You may need to wait longer to see optimal results. The other possibility is that you need more product. I would suggest following up with your injector.

Exposure to the sun, particularly excessive sun exposure, can contribute to the breakdown of hyaluronic acid-based lip fillers over time. It’s important to protect your lips from sun damage by using sunscreen or lip balm with SPF. However, a single day in the sun is unlikely to significantly r...

I tell my patients that they can generally do everything if there is no major swelling just two days after the treatment. Depending on how you feel you should be able to make that decision yourself or ask your treating physician for advice. 

Any scratch / open wound can become infected but most wounds - in a health person - heal well on their own and topical antibiotics are enough. Rednees, pain, swelling and discharge from the wound are common signs of infection. I don’t think scratch will make you lose the filler.

Juvederm is hydrophilic which means it is attracted to water.  When you are dehydrated, your lips will be dehydrated as well.  Therefore, laying out in the sun may indeed make your lips appear smaller in the short term.  Rubbing your lips together frequently may also shorten the life of the J...