Your main issue is that your Boulder Breaker is on the low end damage-wise and you're missing a lot of potential Critical Hit Chance and Critical Hit Damage on your gear.
Here are a couple ways to partially solve that with your current gear:
1. Reroll LPH on your Boulder Breaker to +10% damage.
2. Keep rerolling the CHD your gloves until you get 40%+
3. Reroll the vitality to crit on your helm.
The rest of my solutions basically come down to "find better gear":
4. Ideally, your helm should have Str/crit/ww damage for maximum damage.
5. Other than your weapon gem, your amulet is your biggest potential source of CHD at 100% max. Right now, you have none.
6. You can only have crit chance or crit damage on your RoRG (due to fixed stats and the need for a socket) but right now you have neither.
7. Find a Unity with a socket/critical hit damage as a base stat, than reroll the main stat to whichever stat you're missing. Alternatively, you could swap out Unity for a Convention of the Elements ring, forgoing Unity's damage reduction for even more damage.
8. Find a higher damage (ancient would nice, of course) Boulder Breaker.
2
Your pets scale based upon your damage, F/R raises your damage, so yes, the end product is the the set bonus does increase your pets damage, and it is used in the highest ranking carn builds.
You will automatically keep it up constantly as playing the build in the first place requires using a spender every 4 seconds, which is more than enough to constantly keep both parts up combined with your normal dart spam.