You can change your way of thinking or potentially lose her/push her away. I think you would constantly do the same in every relationship though. Its good to have some guard up as you've only been together a short time and you have every right to have scars from your last relationship but don't punish every woman for what ONE did to you.
Trust is earned and you said yourself you have no reason to not trust her. Focus on what good you have rather than worrying about the crappy "what if's".
So, so you think you can tell Heaven from Hell,
blue skies from pain.
Can you tell a green field from a cold steel rail?
A smile from a veil?
Do you think you can tell?
And did they get you to trade your heroes for ghosts?
Hot ashes for trees?
Hot air for a cool breeze?
Cold comfort for change?
And did you exchange a walk on part in the war for a lead role in a cage?