Do you like reptiles? One of the reasons I got a lizard was so the occasional escaped feeder cricket could ravage the cockroach population in my shitty apartment. That mixed with diatomaceous earth has nearly elimated all roach sightings.

You might need a toad for the bigger bugs eventually

Continuously use the roach gel.

That's stuff (of any brand, really) will help a ton, but since you live in an apartment, you'll never be able to keep all the roaches away unless everyone in the complex starts doing something about it.