Boyfriend never wants to have sex

My boyfriend and I have been together for 5 years we have a 2 year old son and I feel after I had the baby he doesn't want to touch me anymore I would say we have sex like 1 time out of like 3 months it sucks I tell him I want to have sex but he doesn't want to there's always an excuse like hes tired or has to get up early for work no matter what I do I dress up he doesn't pay me any mind I just feel not attractive anymore I don't know what to do I have talked to him about it but nothing changes