how to bring up your sex life

My boyfriend and I moved out of state and in together for the first time last August and since then I've noticed a decline in our sex life. At first I thought it was because we spend the first 6 months here on a horrible air mattress but we got a bed in December and have had sex once. When we do have sex it's like he's completely disconnected from me and I could be any one in the world. He finished without caring if I do rolls over and goes to sleep. Normally I have no problem confronting issues but when it comes to sex I'm really unsure of myself.