All my race sails are mildly flat

but sails of my sailing companios comes with nice belly.
What I am doing wrong? The obvious problem is that I am not tuning my sails , only adjusting downhoaus or outhoul

I am the last to get planing and the power from my sails is miserable ( although easy to control in strong wind)
I try to compensate using bigger sails for the conditions , but I suspect the sometimes the smaller is better...
Should I do something with battens ?spacers on cams ? How do you know if battens are setup properly ?How extending may effect ability of cams to flip?
any tips please
I use Severne and NP race ails