We're both insecure

Jill • 18 | high school senior | 6 months in a relationship
So my boyfriend and I are both constantly insecure and think that the other looks at other people (if you know what I mean) although both of us always tell the other that we don't, which is true. We love each other very much and trust each other, but we're both very scared and insecure people. What can we do to help each other overcome this?