Sex In Marriage, the Tables Turned

I have been married for less than a year. I am 24 and my husband is 27. I'm lucky if he will have sex with me once a week. I've tried to talk to him about it, but all he will say is that sometimes he simply isn't in the mood. This doesn't make sense to me. Even if I try to be sexy and flirty, he always just gets annoyed and rejects me. I want to feel desired. I want him to flirt with me. I want to feel some kind of sexual tension ... and I don't think I have gotten that from him since before we became an official couple ... months before we were even married. I'm convinced that he is depressed, because he tends to be more moody than any female I know. And I am hoping that him getting on some anti-depressants very soon will help our relationship improve.