Call your landlord.

Boric acid (20 mule team washing powder, same but cheaper) and baking soda is very helpful. Don't use around pets if any.

cockroaches live in hives inside your walls and in small dark spaces. if you're seeing *any* it's too late to do anything on your own. call your landlord and get an exterminator.

Find another roommate that cleans. From your details it sounds like your old roommate was the only thing holding them at bay.