<human>: Summarize the given text in a few sentences.

I'm 19, he's 21. We live in the same dorm building, and have been friends since September. I knew he was attracted to me, but I wasn't until a month ago, which I promptly acted on and kissed him. We slept together two days later, and now we're hanging out every day, texting, and being generally sappy and cute together and totally in love, it's great.

Here's the thing. I'm his 4th relationship, but he's my first. I keep finding mysesf acting in ways I KNOW are immature or insecure. What can I do to try and move away from these harmful thoughts? For example, we text often, but when he doesn't respond quickly I immediately assume that something I said/did/wrote bothered him. He often has to tell me to stop apologizing for things that didn't bother him at all.

I've been hurt quite badly by guys I was interested in previously: one gave me the silent treatment for several months, one cut off all contact with me out of the blue, one strung me along for most of the months we were together, etc. I'm worried that I'm to insecure, thanks to this history, to have a functional, secure, trusting relationship.
<bot>: Was burned by not-so-nice boys in the past, now finally have a nice one and can't stop worrying he's going to leave me. How can I become more secure?