What's the evidence on Calcium and Vitamin D for bone density?

A recent bone density test came back in the low average range for my age. My OBGYN recommended calcium and vitamin D. I checked with a family member who is a pharmacist, and she says that the benefits of calcium supplements are not clear cut. Regarding vitamin D, I’m in the sunbelt, and spend at least 2 hours per day outdoors during 8 to 9 months a year (early morning, or evening, sun screen between 10 AM and 5 PM if applicable for pool, beach, for example). I’m sure many people on this forum have done their own research regarding the benefits of calcium pills, and I would love to hear what the current consensus is. I exercise regularly, so my bones get a workout from the muscles pulling on them, if that makes a difference. I think the data I was given is that statistically I have an 8% chance of a hip fracture in the next decade, based on the test results.