Am I being too clingy/anxious?

tl;dr: Hello, I’m 19 years old(M) and I live in Turkey. My girlfriend is 18 and lives in Mexico. We’ve been in a long-distance relationship for 5 months, and things are going well right now. There’s a 9-hour time difference between us, so we can’t really talk much during the day. But when we are available, we try to ease our longing with video calls, and I also express how much I miss her through messages during the day. Even though our relationship is going well, I still worry about it. Sometimes I feel like I’m being too much, and I think I might be overwhelming her. Even though she assures me that’s not the case, I still can’t shake off that feeling. Also, she doesn’t think about the future regarding our relationship. Right now, we are both financially dependent on our families, but this makes me feel like she could replace me with someone else. Her not wanting to fully commit makes me feel as if I’m somehow less valuable in her eyes.

The second issue is about cheating. First, I met my girlfriend on an app, and within a day, the conversation turned sexual and we were intimate, after which she blocked me. Then our communication stopped for 6 months, and after she followed me again on Instagram, we restarted talking. This time, things went normally, and now we have a relationship. But even thinking about the possibility of cheating makes me uncomfortable—I can’t help but think about it. I don’t actually think she would do such a thing, but I still feel bad. I think this feeling comes from the way we first met. How can I get rid of this feeling?