Marriage and sex

My husband and I have been married for a year and a half and expecting our first baby in January. Our relationship is perfect with one exception, our sex life is nothing to write home about and I want to change that. It's been a problem for awhile, he never wants to and I'm always the one that does and when he doesn't I get upset which leads to frustration between us. I think a lot of it for him is psychological, I'm terrified of suggesting different things or trying different things bc I don't want to upset him. I saw someone suggested the book "the act of marriage" does anyone have any other suggestions that worked for them? I love him so much and just want some steamy sex to put the romance back into our relationship.