Starting slowly

Hello Fellow Hiprunners,
I had L THR February 16, 2016 after several years of increasing pain. The months before my surgery I couldn’t really even walk slowly for a mile. I have been a very competitive runner for many years. I marathon to track distances, 1500 and 800 as a masters runner. My doctor told me that if I “have to run” to wait 6 months to ensure that bone as completed growing. I am in my fifth month now and today I ran and walked a total of about 5 miles. I am running slowly and for very short distances. I also take spin class 3-4 times per week, and swim. I wasn’t going to even try to run after the surgery until I found this website and began reading about all the successful running stories. I had my 4 month check last week with x-rays and everything looked great. Basically the doctor and nurse advised that high impact exercise will put stress on the spike and pressure on the bone that could cause loosening, they also worry that the plastic in the inner joint will wear too fast causing a revision. I guess I wonder why others don’t worry about these things in all of the discussion I have read on this site. Have others received similar warnings from their doctors? The running feels pretty good, if I maintain a slow pace, but I will keep going slowly until six months as I was instructed…well sort  of as I was instructed.