Is it normal that i get extremely jealous over everyone i know?

All throughout my life I would get very jealous if anyone else had my loved one's attention. I don't know why, maybe it's because I never grew up in a structured household with lots of love and I was always a loner in school (still am in college). I always just feel very insignificant and worthless and I get jealous when people seem to like someone more than me or leave me behind for someone else. For example, I would get jealous and angry if my parents talked to another person my age and looked like they liked them more than me. I even got extremely jealous when my cousin was born and their attention was so focused on her and they sort of forgot me. I also get jealous when my friends talk to someone else more than me or choose to hang out with someone else. But the person I get the most jealous of is my boyfriend. I freak out if he talks to another girl (due to his flirting and untrustworthiness in the past) or even looks at her. Once I even got jealous when he talked to another guy because he seemed happier than when he's with me. And I get angry if we watch a movie and a naked scene comes on and he doesn't look away. I don't know why I'm like this. Has anyone had similar experiences?