It's possible you are defeating your own strategy. If you bomb AND bait, then the bait won't work. The point of the bait is to NOT kill quickly, but to allow the poison to get back to the nest where the dying roach is eaten by other roaches which then kills them all. So if you bomb them, they die in the open and don't ever get back to the nest.
I suggest you get some of the high efficiency bait roach as noted in various thread above (NOT the kind of thing you can buy in the supermarket) and give it time to work. It's not instant.
Also, you need to remove ALL kinds of food and water. Everything. And you possibly want to look outside your place too. Are you right on top of a restaurant? Do you have neighbours who put food rubbish out in the hall? All of that will affect how long it takes to get rid of them.