Sex problems

When My husband and I were girlfriend and boyfriend, I used to have sex with him almost every day and I was always horny and stuff but as soon as I got pregnant my sexually life dropped dramatically. I am 25 year old and I dont feel horny anymore, I don’t initiate sex no more, I love my husband and he is attractive to me but Im frusrated because he ask my why and I dont know whats going on. My son is 3 years old and we having problems the same amount of time. Could anyone help me understand and can relate about it? I need something 😞