Basically your friend is doing it wrong and you're doing it right. A small, stable pop is great, don't change what you're doing (not sure why some people are telling you to add ollie or do other things, you're already doing it right).
There's a reason you're stable, while your friend is off balanced and unstable in the air
Jumping isn't about getting a huge amount of air, it's about getting a clean, stable air that lets you land in the sweet spot of the landing. If you're already doing a pop (which you are), and you still need more airtime to get to that sweet spot, just increase your speed.
Never copy friends in the park unless they really know what they're doing... most people suck at freestyle and are doing a lot of things wrong.