Fillers in my lips are only lasting 2-3 weeks. Need help! (Photo)

It seems that you metabolize the filler faster than normal. A full cc of filler is typically enough to render a pretty nice result. If indeed you are just metabolizing the material fast, then you should talk to your plastic surgeon about permanent lip implants. These are silicone implants that are placed into the upper and lower lips to provide volume and shape. It's worth discussing. I wish you the best.

If the filler isnt lasting try a more prolonged filler like Voluma or Juvederm Ultraplus or fat injections that are more permanent.  I wish you the best. Dr. Emer.

It's very unusual to have the filler completely metabolize in that short period of time. Either most of your results are from swelling (not the actual filler) or you are breaking down the hyaluronic acid faster than normal- which would be unlikely but possible. It's important to see exactly how much filler is being injected, and where under the skin it's being placed. If the filler is placed too deep under the skin, the results will be lost. Silicone injections are permanent and would be a better option moving forward. 

I have been using lip implants for over 20 years with great results.  There are a couple of different types, both which look great once the initial swelling is gone.  I believe the implant would be a good option for you.