Husband has no sex drive.

Sorry if tmi. But I feel like my husbands sex drive is so low. We have sex maybe once a week nowadays. We've only been married one year and I'm just so baffled as to why he never wants to. He says he's tired and I understand he works a lot of overtime. But our marriage needs to be maintained and he wants to have a baby. Well we can't get Pregnant without some more sex. I talk to him about it, I've dressed sexy to get his attention, nothing works. Please help. Btw he's only 26. This isn't normal...