Please assist me urgently.

I've been with my girlfriend for a year and a month now, and we're both 19. So far, everything has been going well. Our relationship has been solid—we’ve spent a lot of time together, met each other’s families, created countless memories, and supported one another through good times and bad. However, a month or two ago, I noticed a slight change in her behavior, which made me realize I had been treating her poorly. I had been dismissive, not really listening to her, and focusing mostly on myself. In response, I made a conscious effort to change my behavior—being less aggressive, more patient, and more attentive. But after making those changes, I started to feel uneasy and questioned everything, wondering if I had changed too late. It felt like the closeness we once shared was fading. I began to overthink whether she truly loved me for about a week or two until she reassured me, and for a brief moment, everything felt normal again. However, the next morning, I found myself doubting my own feelings for her, which made it difficult for me to be present with her even when we were together or on the phone. I recognize that my feelings for her are genuine; I've never experienced anything quite like this before. She brings me joy, I genuinely care for her, and I feel safe enough around her to cry in front of her. When we lie together, it feels as though we are a married couple. Though I’ve never been physically close with a girl before, being with her feels natural and comforting. I think my relationship anxiety stems from what I've read about love and relationships, which explains my persistent overthinking and loss of appetite over the last two weeks. I sometimes worry that I don't fully embody what love is supposed to be—like being free of jealousy or envy, because those feelings seem to arise for me, although it’s not specific to her. I realize this is more about my own struggles, and I'm committed to working on myself. I want to strengthen my connection with God and learn how to show love genuinely, because I truly want to be with her. Typically, when I feel stressed in a relationship, I tend to walk away, but this time has been different. Despite the anxiety and stomach aches that accompany me daily, the only relief I find is through distractions like watching YouTube, which is not sustainable. I want to confront these challenges, improve myself, and continue building a relationship with her. I understand it won't be easy, but I don't want to lose someone as caring, beautiful, and good-hearted as she is. We have similar goals, and she teaches me new things, though I occasionally feel envious, which I know is unhealthy. I’m working on being more attentive when she speaks as my attention span has been poor lately, unless I'm really engaged in something. I’m making an effort to put everything aside and listen more actively. I envision a future with her, maybe getting a dachshund and even having kids together. I know we’re young, but I feel a strong connection. I wonder if my childhood traumas contribute to my feelings since she's the first person who has genuinely made me feel valued. I hope that my anxiety is at the root of these feelings, especially since how I treated her in the past doesn’t align with the concept of love. But if it isn’t love, why am I so invested in wanting to change for her and introduce God into our relationship? They say love reveals your flaws, and perhaps that's what I'm experiencing. I’m recognizing aspects of myself that need improvement. There’s a belief that love shouldn’t be forced; yet with her, I experience the qualities people associate with love—comfort, happiness, and a sense of safety. Recently, I’ve been waking up with stomach pain and racing thoughts, which I attribute to relationship anxiety. I believe we might just be going through a rough patch, and if I can stick with it, we might emerge stronger than ever. I notice that the anxiety tends to fade when I binge-watch videos or engage in distractions, but seeing her sometimes triggers my worries because I’m scared of hurting or losing her.