IHave I done my homework, am I ready to settle?

I was involved in a MVA on 5/11. I was traveling 45mph when someone made a left tun in front of me. I hit this person on the passenger side spinning them 180 degrees. The right front of my car hit this person, stopping me instantly and deploying both airbags. The car was deem "totaled" by the other person's adjustor. We have the same insurance company. I am a 54 yo male on LTD disability through my company for severe thumb degeneration. I was taken to ER via EMS. Suffered neck,back, right shoulder and right knee injury. Knee has a two year old arthoplasty and the shoulder a four year old cuff tear with SAD, DCE. Went to PCP next day, given muscle relaxers. X-rays in ER showed prosthesis was in place. Had difficulty turning head to right so i had six sessions of PT without relief. PCP ordered neck and it was fin PCP sent me back to OS for recheck on knee and right shoulder. OS ordered MRI on right shoulder which showed severe strain. OS injected shoulder and sent to PT for ROM and strengthening. Rest and compression ordered for the knee. Knee failed to respond, OS ordered bone scan to check integrity of bone/glue junctions of prosthesis. Nothing on bone scan. Knee pain was making ADLs and was unable to walk as prescribed for exercise to maintain blood glucose levels secondary to Type 2 DM. OS scoped right knee and found damaged synovium which was debrided. Os sent to PT for ROM and strengthening Right knee. Medical provided through health insurance, no word of subrogation. Retail on medical at 40K presently. Have letter coming from PCP how recent blood glucose results may be related to lack of exercising due to knee issues and it effects on my short term health. See OS this week, still having problems with knee whenever the knee is loaded such as ascending/descending stairs and transferring sit to stand and back. I am going to ask him if their will be long -term effects with knee from the accident as well. I had three cars insured at time of injury for 100/300 BI. The other person's mother called and left a voice mail stating she wanted to talk to me. After the claim was processed she never called back. I am assuming she injured the person(her son) who hit me and maybe herself, Can her BI coverage be stacked as well as mine? I have not read my policy at this point. Any suggestions beyond writing a "demand" letter? I am trying to avoid a lawyer.