Desperate and afraid of romantic relationships at the same time

I don't know if this is the best forum for this post, but here it goes:

As of late, I noticed a trend in how I feel when I get to know someone who, in my head, is a possible romantic partner. I'm 19, and have never had any romantic relationship or significant interaction (kiss, sex, etc.) whatsoever. Before, I thought that it was impossible for me to find someone, which made me feel very sad and lonely at the time. Eventually, after a really tough rejection, I decided to take an indefinitely long break from "crushing" on others. During this time, I began to significantly improve other areas of my life: found a nice major in college, got into new hobbies, began to finally see improvements after years fighting my shyness, and even more important: I thought I got comfortable by just being alone by myself. After a while, I thought I was ready to try again.

Recently, though, every time I meet someone interesting, and the feelings begin to appear, I get a sense of desperation to be with that person, the thought of the slightest possibility of not being alone anymore leaves me excited, making me doubt whether or not I actually got over my old loneliness at all. When I notice this, I become afraid of showing it off to the other person and ruining the whole possible relationship, and end up trapped between these two strong impulses, making me start to act weird around them. Sometimes I even hope they reject me, just so I don't end up creating a bad relationship, even though I genuinely like them. If I didn't run away already, the other party seems to notice my weirdness and begins to avoid me. Any advice on what I should do or improve in my life to break this cycle?