Welcome to the forums!

Has she given you reasons in the past not to trust her? Has she lied about anything to you that you are aware of? In other words, is your mistrust of her legitimately supported by her actions? If so, then you can work with her on this issue, and she needs to always be upfront and honest with you. If not, then it's up to you to manage your anxieties, as you already are aware.

I have mistrust of my husband after a near infidelity, so I can relate to your feelings. I have mistrust of him now and it creeps into our relationship. If he's on his phone all day long, I want to know what he's up to. And if he goes outside to call someone, I want to know whom he's calling. If a good looking woman works with him, I want to know if there is any flirtation going on. After a while though, this behavior on my part becomes tiresome and annoying to him. At some point, I need to choose to trust him again because he's given me no real reasons to not trust him lately.

I would work with your therapist on this issue. A therapist can have good suggestions on how to manage and cope with your anxieties without projecting them onto your girlfriend. At least I would hope that your therapist is helping you in this regard.