@Marissa I don’t know how to start it and what to say, as we don’t have that culture.
That's fair.
Sex is so important for a relationship so even if it's awkward you have to have a talk with him. Maybe even just ask him to have a date with you since he is so busy with work and let him know you just want some quality intimate time with him and see what happens.
At the risk of sounding obvious; have you tried talking to him? This was me and my husband but we finally talked about it and now I'm almost 6 weeks pp and he's itching for touches.