Leg drive is easy to forget about - especially if you’re new to the bench press - but it’s important. Your legs give you lateral stability (the bench doesn’t help much here as it’s not very wide), they support your arch, and they help make everything between your feet and your shoulders that much more rigid, which makes for a more stable platform from which to bench.
So use your legs next time, and if you find that you keep forgetting, write “leg drive” down in your training log as a cue for yourself next time.