i was rear ended, the car that hit me was going between 20 a

I was rear ended, I was going between 3 and 5mph, I was letting a vehicle turn from a side street, the car that hit me was going between 20 and 25mph, I think the driver was texting. I had a grade 1 spondololisthesis of the l5s1, I know have a grade 2 with painful restriction of the low back. I also have tears of the infraspinatus, coracohumeral ligment, and subcapularis muscle tendon with mild persisting restriction of the neck. I'm trying to put off a rotator cuff surgery as long as I can stand it. My medical bills with pt are around $15000. How do I calculate future surgery, pain and suffering, loss wages? What is it worth?