Lol help

Ok, so I’m 19 and have never been in a relationship. Well 1 in 8th grade that lasted a day. But I’ve had multiple crushes obviously, and I can like them for so long and then when they show interest in me, all my interest is gone. I feel so uneasy around them and I don’t know why. I want a boyfriend and to do cute relationship things but the idea of actually being in a relationship is terrifying to me. I’ve started talking to this kid and he’s mentioned kissing (keep in mind I’ve never done anything more than hug a guy) and I was like well I wanna get to know you more. He seems pretty understanding but then says something like “you know what else I wanna do” and I’m sure it’s just flirting, but I’ve never had a guy genuinely flirt with me so I get super uncomfortable and try to change the subject. I know guys are going to want sex, but I’m not ready for it yet. I want to be able to experience the small things in a relationship first and see if it’s the right person. But I feel like if I ever tell a guy that they’ll just be like ok bye. I really don’t know what to do.