Problems with being clingy with my boyfriend?

Okay, so I don't know what's wrong with me but I'm super clingy when it comes to my boyfriend. It's not because of trust issues, we've been together a year and a half and I love and trust him more than anything. We're long distance though, so a lot of our communication is over the phone. I don't know why, but I get upset when he doesn't text or call me for a day and I worry that he doesn't want to talk to me. Like if he doesn't text me, I literally get anxious and I'll think about it all day. Sometimes I'll text him as a result, sometimes I won't. I'm completely aware of the fact that it's not normal to be like this and that he needs space so I try to deal with it by myself. I also get kind of nervous because I feel like I almost always want to talk to him and have no problem texting him whenever so I worry that somethings wrong because it's not really the same for him, he told me he needs a break from his phone sometimes so I try to be understanding. We're in high school but he does have a weekend job. It's not bad that he doesn't text or call me for a full day until late at night right?  What's wrong with me? How can I stop being like this?