How to get his trust back.

To make a very long story short I love my boyfriend and want to marry him and spend the rest of my life with him. He’s an overall amazing and pure guy. Today is our two year anniversary but he has some trust issues that we’re working on. Over span of the two years we’ve been together we I have broken his trust a lot: I lied about being a virgin(I’m his first gf and he was a virgin and flirted with a couple of guys behind his back(including some exes) that he found out about. I’m willing to change and he has forgiven me a ton of times but still in the back of his mind I know he’s not completely confident in me. How can I get his trust back?