Hardly any sex😢

Sometimes I wonder if there is anything wrong with me😥 I feel like I'm attractive... I'm loving and I get along with just about anyone, we have been married 3 months.. Together for almost 7 years.. I am 23 and he just turned 24 today. He works a lot.. Away 3-4 days a week, he works at the hospital 12 hour days and on call at night. We've talked before and asked why we aren't having sex and he just tells me he isn't confident. I feel like he has a lot of confidence in other areas. I ask again but it just makes him mad. I don't feel like I ask for much. It just makes me sad.