Insecure Girlfriend

My boyfriend and I have been dating about a year now. I trust him but I have been cheated on by my past 3 boyfriends so I always have that little doubt in the back of my head that he is doing something behind my back. He understands this as we’ve talked about it and I’ve gone through his phone a couple times just for reassurance and of course there’s nothing suspicious there. He does seem to be having a lot of conversations with other women though over social media. Just small talk, but it still bothers me because 90% of the time it’s him initiating the conversation. He’s a social person, so should this really be bothering me or am I just that insecure? Lol I need advice because I’m feeling a little crazy