Trust issues...

I have known my boyfriend for over 7 years now. He started to pursue me 3 years ago and finally we are in a relationship which started almost 6 months ago. Everything is amazing. He's lovely, kind, patient... We are happy together however, my trust issues are beginning to be a problem. My past relationships were really bad and unfortunately it's effecting my current relationship. I love him loads and want to be the best girlfriend I can be but my fear of being mistreated or cheated on just gets out of control. Has anyone else had this problem or have any advice? I worry far too much... Please help if you can.