You need to provide more information.
As mentioned above, you need to determine how much current the motors draw.
If you have a watt meter, you can tell us directly.
If not, at least tell us which prop you are running.
Here is a video of the manufacturer using a watt meter and a thrust meter to demonstrate the current draw and thrust with various batteries (3s and 4s) and various props.
From the video
Gemfan 3545 BN prop pulls 5 amps per motor.
Gemfan 4045 BN prop pulls 8.5 amps per motor.
Watch the video. There are a lot of different props they try.
Either watt meter your motors or tell us which prop you are using. Then we can talk about battery size and flight times.