Is there a possibility for one of you to change shifts ? If not , well then you just need to find a hobby or something that keeps your mind busy and off the fact that you have limited time together. Hang out with friends , take a course somewhere on a topic that interests you , art ? writing> book clubs?
You do need to find a way to be happy when you cant see your boyfriend.
Do you see a Therapist? If not that is a great place to learn how to deal with your dependance on him. I'm not saying reduce your love and wanting him to be with you, just avoid being dependant on him to fill a void you have.
Therapy is a great place to learn things about you that you didn't even know about yourself, coping skills to help you manage the times when you aren't able to see him.
I hope your able to find ways to enjoy life even though for right now you guys are just on a lousy off hours situation.
Welcome to PC