Marriage Sex (I want more)

I been married for almost 4 years, I’m 29, he is 35. We didn’t have sex before marriage, but we enjoyed each other with some oral sex and fingering. I gave birth 1 year ago and lately my husband don’t want to have sex with my regularly, we do it less then 4 times per month. I want to have more sex since we wait till marriage, but he is not in the mood, (that is what he says). We use the the natural planning method, that means that we can have sex certain times per month. We have talked about the fact that I want more sex and he said that he will put more effort on it but the month ends and I don’t see any improved.

The thing is that when we have sex I really enjoyed.

I don’t know what to do or what to tell him so he can be more sexual active. Any opinions...