On my other phone and tablet its a round white button with 6 dots in it. App button. When you push onit shows all your apps and you pick what you want to bring up to the home screen.
That's your app drawer your referencing. Are you running Android Nougat (v 7)? If so, go to your settings, then navigate to Home screen-> Select home-> then select the option listed as Home with seperate apps list. This will bring back the app drawer. Also: I do not know if this will alter your home screen customization.
Welcome to Android Central! Which phone do you have? The customized launchers from certain manufacturers got rid of the app drawer (like Huawei's EMUI), which makes the phones act more like iPhones :-\.