S.O going clubbing?

I'm 18 and I have been with my boyfriend for almost 2 years. I work in a bar Thursday-Sunday every weekend so I work sociable hours so I never really go clubbing except when I get the odd Friday or Saturday off but my boyfriend goes clubbing at least once a week because he has Saturdays and Sundays off and I get really annoyed and worried. Hes never cheated but hes done sketchy things over text while we were supposedly on a break and I just dont trust him and he knows this. But when he goes out i always get scared that girls are going to try something with him and I know he wouldn't cheat but at the same time if someone did try something he probably wouldn't tell me. Any advice on how to not be so worried every weekend when I'm in work and hes at the club?