Susan, most of us use supplements with heavy duty drugs. There are those who report dexa success with supplements alone. And those who fracture meanwhile.
Though this is a cautious group, Mayo connect seems a little pharmaceutical leaning.
The commenter I've found most compelling in the natural group is @kathleen1314. She has done extensive research on strontium citrate.
I was too afraid of fracturing, so I'm on Forteo.
At 77 with a -3.5, you've done well. We tend to lose the most bone between 52 and 62, because of estrogen loss.
Best wishes.