How can I get my boyfriend ot be more dominant in the bedroom without having to ask him ?

Instead of trying to indirectly tell him just make a game out of it. Tell him you want to be dominant sometimes, and other times you want him to be dominant. Switch it up. Also you may want to consider his physical and emotional health. Maybe he hasn't been feeling well or he's sad about something. If none of this works then just come out and tell him. If he really loves you then he won't want to disappoint you. So, if you have to tell him just be nice and sincere.