None of us here can answer your questions to be honest. We can suggest possible scenarios but nothing more. Your best bet is to get a professional to look at it and, if necessary, carry out the appropriate diagnostic imaging (X-rays, MRI, or whatever is felt to be the best option). As the initial injury was 2 weeks ago, you are no longer an emergency, so starting with your primary health provider is the best idea, your GP/MD.
Just as an indicator though, it is unlikely that you have "severed a nerve", more likely that you have as a minimum a pretty hefty bone bruise which could be exerting pressure on the peripheral nerves, resulting in the numbness. Bone bruises are extremely painful, especially if they are in a pressure loaded part of the leg and can take anything up to a year to finally heal.
As you say you have no mobility problems, just the residual lumpiness and numbness, you may have a problem getting a thorough examination due to the length of time since the injury and your apparent functionality. Stick to your guns and get an X-ray at least to show that you have not fractured your knee cap. The kneecap is a sesamoid (sp?) bone in that it is fully contained within the patella tendon and it develops after we are born. Direct impact on to it can fracture it so pushing for an X-ray will at least eliminate that.
As for helping the healing process, ice and compression are good for reducing swelling. As you can use the joint without any problems I would not suggest rest and elevation right now as that unfortunately leads to muscle loss and other related problems. Continue to use your knee/leg as normal unless it is painful or your symptoms get worse. The joint is better the more you use it as normal, but do not push it too hard until you have a clear diagnosis. Take a look in the patella section of the Information Hub here and educate yourself about the anatomy and function of the knee and kneecap in particular.
Hope things are harmless and that you have no further problems!