How long is your flight time?
You really cannot expect long flight times with this setup. You have the weight of the gimbal, the gopro, and the gimbal is drawing juice. I had the same setup(except with gopro 3 black)... and basically after 4 minutes I was already in the caution zone.. not taking it up too high, not too far away.. max duration was 6 mins. That may have not been its max, but once I see the red flashing when I almost full throttled to full throttle, I change the battery.
I got the 9443s now though, and basically after each flight my gopro reads 8-8+ minutes of recording. That's a big difference imo. Still, after about 5-6 minutes I don't take it far away or high.
The first thing you should do is stop expecting long flight times with a gimbal equipped with a gopro with the stock battery and stock props.
The second thing you should do is order 9443s or 9450s and about 4 more batteries.