11 days post lower face/neck lift, I swole up under my chin like a bullfrog. Is this amount of fluid retention normal?

Yes, you may still have swelling, which can last 3-6 months after your procedure. To speed up healing, you can try adding hyperbaric oxygen, lymphatic massage, venus legacy or exilis radiofrequency treatments. To improve final results, we will often do a kybella and ultherapy about 4-6 weeks after neck liposuction to get more of an outcome. See an expert. Best, Dr. Emer

Very difficult to say what is going on, even if you did include pictures. It does not sound normal - always best to return to your surgeon and get checked for things like this. It may be normal but also could be a fluid collection or bleeding under the skin.