Vitamin D intake, just diagnosed seeking information

Having just been diagnosed with having osteoporosis, despite a very active life syle and weight bearing exercise, I am unsure of many of the do and dont's of calcium supplements etc.

How important is taking Vit D with a calcium supplement? How much Vit D should I be taking? Can Vit D, have any negative effects on the body if I took too much?

I see that most calcium supplements, have Vit D added. I want to increase my Cal. Citrate, but am afraid of the increased amount of Vit.D included in the pills.

I do not have a health care provider currently overseeing how much Cal.citrate I should take. My BMD T scores indicate an average of -2.0 It seems that according to info. found of "levels" I am still boderline. However, how do I proceed in seeing that this does not become osteoporosis?

Any suggestions would be so appreciated.