How can I be more trusting

I’ve been dating someone for over 3 months and we’re in love. It’s the greatest feeling and we’ve talked about living together, marriage and kids however those are a little way off yet because I have a son who she’s not met just yet as we’re trying to enjoy it being just us for now. She has met my parents and we’re making arrangements to meet each other’s friends

I seem to have an overriding concern that she’s going to cheat on me and I don’t really know where it’s come from. She has her own things she does with her friends; nights out, trips away and she’s off to a festival next weekend with her friend with two nights camping.

I’ve spoken to her about whether sexually I am satisfying her and she was very reassuring. She’s had more sexual relations that I have (she says it’s not triple figures) but we are both very sensual people. She’s told me that she once cheated while with a boyfriend when they both went to University and were miles apart but that’s the only time.

I feel like I do trust her, as in I don’t think she’s seeking it from elsewhere, I do just worry that in situations where there’s drinking and potentially men trying it on that she may get lost in the moment but I know that thought is more from my insecurity than anything she’s done to worry me

So I want to say I trust her because it takes two to tango, however even telling myself I trust her I worry and overthink about these events.

I guess I’m more looking for advice on how to not worry about this as much, and in general have a bit more self confidence about our relationship. I feel so in love with her it’s scary to imagine losing her, so why do I think about that happening and how can I make that stop?

We do message every single day (I reply when I see messages, she’s more likely to wait than rush a response) and we try to speak on the phone at night as much as possible which equates to a quarter to half of the time