Free T is measured by total T and SHBG.
If your FT is low, your SHBG is most likely elevated.
SHBG is difficult to manipulate sometimes. Lowering estrogen may lower SHBG and free up more T.
There are several other factors to consider as well.
Inhibited thyroid function will elevate SHBG.
Insulin resistance will elevate SHBG.
Danazol has been shown to lower SHBG.
Google "Dr. Marianco SHBG"