It's not maxed out, and happy plants are growing plants. Plants that aren't growing are dieing. Your fig's growth potential is being limited by cultural influences that need correcting; and correcting cultural conditions that limit our plants is our only job when it comes to ensuring good vitality.

While your fig doesn't truly go dormant in winter, its winter and early spring growth potential is considerably less than its summer growth potential. Tight roots and/or saturated soils can cause it to almost completely stall, no matter the time of year. Potting up is a half-fix, and only partially alleviates the limitations imposed by tight roots, so a true repot, which includes bare-rooting and a complete change of soil, is undoubtedly the way to get your plant to change to gears. Do this in the summer for best results and fastest recovery. Depending on where you live, it would best be repotted between Memorial Day (in the US Deep South) through Independence Day (in more northerly climes).

Getting it to branch and remain as full as possible requires keeping the tree as healthy as you possibly can and an easy to learn/follow pruning/pinching regimen. Let me know if you're interested in making a plan.

Al