Age differences

I just recently started seeing a 19 y/o and I just turned 22. He's mature despite his age and really has a lot going for him.. Of course it helps that he is crazy about me too. I have very deeply rooted, ugly trust issues though and it makes me skeptical of anyone who tries to be involved romantically and I overthink all situations. I know he's not messing w other females and he has a busy schedule but I keep questioning whether or not he's really emotionally invested like he thinks... And I think the only reason I do this is because he is 19... I'd also like to talk to him on the phone but after 12hr shifts he's really never up for it.. I'm just wondering if anyone has some advice for tackling my trust issues and communicating w him what I need to feel more secure in the relationship.