When am I always so insecure when my boyfriend spends time with his female friends?

We're both 20, in uni and have been together over a year. Everything's going great and we really enjoy each other's company when we see each other. The thing is, we don't see that often, because we go to different universities and I also work 3-4 evenings a week. Also some weekends we go to our family homes, which are not in this town. So all in all we see like once a week.

During the time we're on our own, he spends a lot of time with girls. That's because there are many girls in his major and he's always had many female friends. They're all mostly nice people and I trust my boyfriend completely and know that he wouldn't look at me like he does if he didn't love me. Still, I can't help but get nervous sometimes. Most of the girls are much prettier and much more interesting than me. And his 2 best friends, also girls, are very close to him, as in, he spends all his time in uni with them and often goes out with them to bars or something. Am I weird for being a bit anxious, even though there isn't any serious reason for that? I'm a girl and most of my friends are females.