I sometimes feel a strong need to push my girlfriend away. What's my problem?

I'm 25 years old and I had never been in a serious relationship before her. Deep down I always wanted to have a serious relationship, but I never met anyone who truly made me feel something special (and that felt the same for me). This all changed when I met the most wonderful girl I've ever met... We became best friends, I started to fall for her, and then we decided to try being together. I'm also her first serious relationship. Unexpectedly, we have both been very good at this relationship. We have a very open communication, we trust each other very much, we are not overly jealous, we give each other the right amount of space, instead of fighting or arguing we always talk about things in a constructive way and try to find the right compromises, etc. We are both insecure, but we've more than managed! All in all, I've never been happier! The way I feel about her is something I never felt before and I truly feel like this is real love from both sides. I can just feel it. The problem is that sometimes (not very often) I just get an unbearable urge to push her away... For example if she texts me something nice something in my brain tells me to ignore her... When we won't see each other for a few days, something in my brain just tells me to not text her and reply in a cold way if she does. I'm 99% sure she loves me as much as I love her (there always has to be some uncertainty, right?), but in those moments something tells me that she doesn't even care about me and that I should just get away from her and not say a word. Sometimes we have plans to do something and I feel the urge to just cancel... Luckily, it's very rare and there's also a good part of me. I made a promise to myself never to act on these weird feelings, and I have been able to do it 90% of the time. But I feel incredibly bad for even having those thoughts, I never want to cause her any kind of hurt! I asked her recently how she thought our relationship was going and she said everything was just perfect and she was very happy, so we're on the same page. But why do I get these urges!? Is it insecurity? Fear of being hurt? Fear of commitment? Fear of losing her somehow? Fear of being vulnerable? I'm angry with myself at the moment, because I just want to be with her and make us happy without having those bad feelings.

Yeah something like that sounds like it should be my problem... How can I fix it? The worst is that sometimes whenever she does something that's completely fine, I find the way to convince myself that she doesn't really love me. And sometimes I believe it. We've been officially together for 3 months, but it's been about 6 months since we talked about our feelings for each other. I just want to be normal! Or is it that the relationship is not what I need right now?

I'm just trying to understand why I get like this... 1) I feel happier when I'm with her. And I feel fine when I'm away from her, I don't feel like I need her to be happy, but I do feel happier when I'm with her. 2) I feel stressed when I get these thoughts, but otherwise I feel really happy when I think of her or when I'm with her. 3) I don't feel trapped, I just feel very vulnerable and (at those moments) I feel like ruining it because I feel she doesn't care about me. 4) I never cared about being single, but I definitely don't miss it right now. I feel so much better with her.

Okay, I just realised that when these weird feelings show up is when I feel that I care more about her than she cares about me and I feel like I'm putting more effort than her. Overall I think this is an unfair thing to say, but in those moments that's how I feel and there's no way to convince myself otherwise...

I was thinking of talking with her, but I wanted to understand first. I guess I'll have to talk to her. Whenever I don't have those weird feelings, I know that we're both trying equally hard to make it work. But yes, I'll try to talk with her about it if I'm not able to overcome them soon.