how to stop being clingy?

I'm clingy when it comes to my boyfriend for some reason and I'm pretty embarrassed by it. we're long distance, and only get to see eachother once and a while. If he takes too long to reply to my texts (3+ hours) I get kind of mad/anxious. We barely ever get in fights and the only fights we get in are about this, because he's busy and I'm clingy so it clashes once and a while. I'm a huge over thinker and a super anxious person, so whenever he doesn't reply/texts shorter than he normally does I get anxious that he doesn't want to talk to me anymore. I know it's ridiculous, I'm just terrified of losing him. I think it annoys him because he's pretty busy and not necessarily one to always carry his phone on him. how can I stop being like this? 😪