Not Having sex

What should I do my husband and I been together for 3 years and married for 1 year my husband don't look at me sexual any more and he don't ever want to have sex with me.... I love him so much but he don't show it he says he is tired and he is not on the mood we both work but I try to be intimate with him on my days off and his days off and still nothing I tried a few things to spice it up and still nothing. I just want to know what I am doing wrong I am almost 21 years old and he just turned 26 years old.... we have 2 kids of our own and we have temporarily custody of his 2 nieces too.... he don't do anything with me no kissing on me no nothing the only kisses I get is when he's leaving for work or one of us go out with friends or just to go to the store that's it.... I need so advice or what do you lady's think....