Sexually frustrated

My husband and I got married this year in march. I love him to pieces and do all I can to show him. He's very good to me and my 2 daughters and we have fun together and share similar interest. But our sex life is almost non existent. We are newlyweds and I don't understand how this is happening so early on. We can have the best day and have lots of laughs, but when it's bed time he will cuddle me but that's it. I've tried to talk to him and he gets so offended and defensive. It's starting to lower my self esteem a lot. I've gained some weight so that's another thing I'm dealing with. Is he just losing interest in me bc I've gained weight?! I've caught him looking at other females pics on social media and it crushed me. I love him and can't imagine myself without him. But I'm only human and I need Intimacy with my husband 😢