More sex

Okay so me and my bf have sex at least 3-4 times a week but ladies I want it more. We'll have sex once a day and that's enough for him but sometimes I want to do it again but I'm afraid if I try to initiate it he'll just turn me down.. I'm 33 and he's 21 so I would think his sex drive would be up to where mine is but it's not and it kind of bums me out. My sex drive is at an all time high right now. I had to buy myself a dildo just for when I'm not around him bc it seems I'm in the mood almost all the time. How do I go about talking to him about this? I don't want to make him feel ashamed or uncomfortable but i feel it needs to be discussed.