which meds for 39 yr old patient with steroid-induced osteoporosis?

I am a 39 yr old woman with lupus and have been on and off (mostly on) steroids since age 7.  I have also been pregnant and/or nursing for the past 4+ years.  I recently had a bone density scan with the following results: hip, BMD=.603g/cm3, T-score = -2.8; lumbar spine, BMD = .716g/cm3, T-score = -3.0; forearm BMD = .461g/cm3, T-score = -2.0

It has been recommended that I begin treatment, with my PCP advocating Calcitonin (which I had tolerated in the past) and my rheumatologist recommending either one of the bisphosphonates (no preference) or Forteo.  How do I decide which is most appropriate for me? The relative risks/benefits are not entirely clear, but I would think that at my age building bone would be a priority?  I am not opposed to injecting myself daily.  On the other hand, do the bisphosphonates carry less overall risk?  Or the Calcitonin, even though less effective, since this will likely be a long term therapy?  Or some combination over the years?  Thank you for any guidance.