Is it normal to think about your not recently passed father?

Hi, my name is Wisteria and my father died when I was 3 years old. He died because of a drug overdose and I was little so I didn't know what that meant, then I started having dreams of him coming back one day, and I still have them all the time. My Father and Mother were not married and I was an accident, but my mom idi not care because she already had a child with her ex-husband, and it makes me feel a little better but I still wonder if my Father overdosed because he didn't feel like he could take care of me, or he couldn't handle having a child at such a young age (he was 20 and my mom was 28). I really need some help, please.(please be nice about your response, and no I don't think of suicide, ever, well, maybe sometimes..) My real Parents were very addicted to drugs, but my Mother did lots of rehab and is still sober, but my Father didn't think to get rehab because he believed that it would not work( I'm guessing ). And my real parents were very happy until my Father died of an overdose, now I have had 2 step dads and my current step dad (#2) is very strict and I feel I have not had a good life.